UNIVERSITY OF ILLINOIS 


Agricultural Experiment Station 





BULLETIN No. 186 





A GENERAL SURVEY OF THE MAY- 
BEETLES (PHYLLOPHAGA) 
OF ILLINOIS. 


By STEPHEN A, FORBES 
State ENTOMOLOGIST 


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A GENERAL SURVEY OF THE MAY- 
BEETLES (PHYLLOPHAGA) 
OF ILLINOIS 


By STEPHEN A. FORBES, Strate ENTOMOLOGIST 


The following discussion is based on a study of the numbers, dates 
of occurrence, food-plants, and distribution in Illinois of 114,493 May- 
beetles or ‘‘June bugs’’ belonging to thirty-four species of the genus 
Phyllophaga, and very nearly all collected by my field assistants in 
forty-two Illinois counties during six of the years from 1907 to 1913, 
no collections being made in 1912. Occasional use is also made of the 
data of 4,224 specimens additional, obtained in central Illinois in 1905 
and 1906, and two tables of the most important of these collections, 
that made at Urbana in 1906, are printed with the other statistical 
summaries. It is the general object of these studies to distinguish the 
several species of Illinois May-beetles (the parents of the white-grubs) ; 
to see which of them are numerous enough anywhere and at any time 
to be notably injurious in the grub stage to agriculture and horti- 
eulture; to learn the food, when in the beetle stage, of these more 
injurious species; and to learn, so far as practicable, what are the 
conditions favoring the increase and decrease in numbers of each 
species, in the not unreasonable hope that a knowledge of these funda- 
mental matters may help, now or eventually, to a solution of the old 
and very difficult problem of the control of economic injuries by the 
_white-grubs. I have also had especially in view.the food habits and 
preferences of our most abundant May-beetles, as related to the choice 
of trees and shrubs for roadside planting and for the home premises. 
Other studies of mine have clearly shown that fields and lawns in 
the neighborhood of trees upon which May-beetles may feed, are much 
more liable to injury by the white-grubs than those at some distance 
from such trees, and it is important, consequently, that those con- 
eerned should know what kinds of plants offer special inducements to 
an infestation of their premises by those destructive insects. 


LOCATION OF THE COLLECTIONS 


Of the forty-two counties from which collections were obtained 
thruout the state, nine were in northern, eighteen in central, and 
fifteen in southern Illinois, those in each section extending well across 


the state. 
215 


216 BULLETIN No. 186 [February, 


COUNTIES IN WHICH COLLECTIONS WERE MADE, AND 
NUMBERS OF COLLECTIONS FROM EACH 


(ToTAL, 1959 COLLECTIONS) 


Northern Illinois 


Carroll, 1 
Cook, 194 
DeKalb, 1 
JoDaviess, 1 
Kane, 426 
Kankakee, 5 
McHenry, 23 


Whiteside, 5 
Winnebago, 5 





Central Illinois 


Adams, 2 
Champaign, 274 
Coles, 2 
DeWiitt, 8 
Hancock 6 
Iroquois, 8 
Knox, 380 
Logan, 1 
McDonough, 4 
McLean, 252 


Southern Illinois 


Alexander, 8 
Clay, 3 
Gallatin, 4 
Hamilton, 4 
Jackson, 144 


Marion, 21 
Massac, 3 
Perry, 32 


Pulaski, 10 
Richland, 13 


661 Macon, 1 St. Clair, 5 
Mason, 2 Union, 24 
Morgan, 3 Washington, 29 
Piatt, 1 White, 11 
Pike, 5 Williamson, 2 
Sangamon, 3 — 
Vermilion, 29 313 
Warren, 4 
985 


The localities from which specimens were collected within these 
counties were twenty in northern, forty in central, and twenty-four 
in southern Illinois—a total of eighty-four separate points or stations. 
By far the larger part of our material was obtained, however, from 
Aurora and Chicago and its suburbs in northern I1linois, from Cham- 
paign, McLean, and Knox counties in the central part of the state, and 
from Jackson, Perry, Washington, Union, and Marion counties in 
southern Illinois. In these ten counties, indeed, nearly 97 percent of 
all our collections were made, only 142 of our 1959 lots of specimens 
coming from the remaining thirty-two counties. 


NUMBERS OF SPECIES AND OF SPECIMENS 


The total number of species recognized in the state was thirty- 
four, not counting for the present nineteen specimens as yet undeter- 
mined. The number of representatives of these species varied from 2 
specimens of hirtiventris to 48,439 of lirticula. Our collections of 
the sixteen most abundant species amounted, in fact, to 97.9 percent 
of the total number of the thirty-four species, and those of the ten 
most abundant species amounted to 91 percent. In the northern sec- 
tion of the state we took 15,457 May-beetles, belonging to twenty-one 
species. The five most numerous of these species were represented by 
84.8 percent of the entire number, and the nine most numerous, by 
98.2 percent. In the central part of the state we collected 78,915 


1916 | MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 


tN 
—_ 
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May-beetles belonging to twenty-seven species, the first four of which, 
in order of numbers, were represented by 91.1 percent of the whole 
and the first six by 98.2 percent. In southern Illinois our 20,121 
specimens belonged to twenty-eight species, the first nine of which 
were represented by 87.2 percent of the specimens and the first four- 
teen by 97.2 percent. 

It is evident from the foregoing that only a comparatively small 
number of these species of our rather long list have, in any section or 
location, any special significance either as economic or ecological fac- 
tors in the general system of life, and to these more abundant species 
principal attention must be given. 


MAY-BEETLES OF THE THREE SECTIONS OF THE STATE 
IN THE ORDER OF THEIR ABUNDANCE* 


Northern Illinois Central Illinois Southern Illinois 
(15,457 specimens) (78,916 specimens) (20,120 specimens) 
Fusea, 4356 Hirticula, 40,484 Forbesi, 3,367t 
Futilis, 3197 Implicita, 14,222 Hirticula, 2,874 
Rugosa, 2326 Inversa, 9,762 Micans, 2,671 
Anxia, 1959 Fusea, 7,442 ‘  Implicita, 2,040 
Inversa, 1259 Futilis, 4,547 Bipartita, 1,719 
Implicita, 718 Tristis, 1,037 Fraterna, 1,448 
Tlicis, 560 Rugosa, 410 Vehemens, 1,405 
Tristis, 523 Tlicis, 234 Profunda, 1,335 
Drakii, 279 Fervida, 174 Fervida, 682 
Hirticula, 81 Drakii, 142 Futilis, 556 
Nitida, 76 Crassissima, 97 Crenulata, 503 
Crenulata, 54 Anxia, 82 Corrosa, 475 
Micans, 19 Crenulata, 73 Tristis, 324 
Congrua, 14 Horni, 66 Congrua, 175 
Forsteri, 9 Fraterna, 58 Delata, 106 
Villifrons, 8 Vehemens, 21 Tlicis, 79 
Prunina, 8 Prunina, 19 Anxia, 75 
Fraterna, 6 Forbesi, 13 Crassissima, 68 
Balia, 3 Micans, 10 Forsteri, 60 
Corrosa, i Bipartita, 6 Praetermissa, 55 
Fervida, 1 Balia, 5 Rugosa, 33 

Calceata, 2 Longitarsa, 15 
Barda, 2 Arkansana, 11 
Congrua, i Calceata, 8 
Forsteri, 1 Drakii, 8 
Villifrons, 1 Prunina, 6 
Profunda, 1 Barda, 3 
Undetermined, 3 Hirtiventris, 2 

Fusea, 2 

Undetermined, 16 


*The nomenclature of this list, and of course of the entire paper, is that of 
Dr. Robert D. Glasgow, as given in Article V, Vol. XI, of the Bulletin of the 
Illinois State Laboratory of Natural History. (For synonymy see column of 
remarks in table on p. 239.) 


tSpecial collection of 352 specimens obtained in 1911 not included. 


218 BULLETIN No, 186 [ February, 


IMPORTANT SPECIES, GENERAL LIST FOR THE WHOLE STATE 


Hirticula, 43,439, central and southern 
Implicita, 16,980, eile. “8 
Fusea, 11,800, northern and central 
Inversa, 11,021, if a be 
Futilis, 8,300, & at a? 
Forbesi, 3,380, southern 

Rugosa, 2,769, northern 

Micans, 2,700, southern 

Anxia, 2,116, northern 

Bipartita, 1,725, southern 

Fraterna, 1,512, 4 

Vehemens, 1,426, 3: 

Profunda, 1,336, eo 





108,504 — 94.9 percent of 114,493 


METHODS OF COLLECTION 


With the exception of those picked up from the ground in fol- 
lowing the plow, our May-beetles were, of course, all collected at night, 
those at light-traps and electric lights early in the evening, as a rule, 
when the beetles were flying freely, and those from trees and shrubs 
generally after the night coolness had made the insects sluggish and 
ready to fall to the ground when jarred or shaken off. Generally 
speaking, no attempt was made to select the trees and shrubs from 
which collections were made, but possible food-plants of the beetles 
were taken indiscriminately, as my collectors chanced to come to them. 
The 1906 collections and a part of those of 1911 are exceptions to 
this statement. Records were made in every case of the date, place, 
and method of collections, and, if obtained from plants, of the kind 
of plant from which each lot of specimens was gathered. 

It was not possible to assign any single assistant or group of 
assistants to this work, but those favorably situated were instructed 
to use for this purpose all the time left them from their other em- 
ployments. The product of the work was, consequently, very unequal 
in character as to numbers of specimens obtained in different years, 
at different places, and in different parts of the season. The data 
are especially difficult to organize in any thoroly satisfactory manner 
because the only available unit, the single collection (by which is 
meant the lot of specimens obtained by one person in one night from 
a single kind of tree or shrub), was not by any means of uniform or 
equal value at all times and places, and in the nature of the case could 
hardly be made so even tho great pains were taken to that end. It 
has seemed to me, however, that, with a sufficient number of collec- 
tions from food-plants, this unitary value might approximate closely 
enough to an equal average to make it available for cautious statis- 
tical use, provided conclusions are drawn only where contrasts are 
obvious and pronounced. Such use as has been made of the numbers 
of beetles obtained from lights has had reference only to time and 
place, and not to the number of ‘‘collections’’ recorded. 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 219 


ACKNOWLEDGMENTS 


My grateful acknowledgments are due to the considerable num- 
ber of assistants who made the collections upon which this study is 
based. Those to whom I am indebted on this account are James A. 
West, John J. Davis, George E. Sanders, Wesley P. Flint, Horace F. 
Hudson, Lindley M. Smith, Alexandre A. Girault, David K. Mce- 
Millan, Charles A. Hart, and George B. Howard. To Dr. Wm. A. 
Nason, of Algonquin, McHenry county, I am under obligations for 
twenty-three collections (1280 specimens) obtained at lights in 1907. 
I am also particularly obliged to John J. Davis, of the U. 8S. Bureau 
of Entomology, for data of collections made in northern Illinois in 
1914, by means of which I have been enabled to distinguish with 
certainty the species of May-beetles which were chiefly concerned in a 
general and serious injury to farm crops by white-grubs in that part 
of the state in 1912. The determination to species of the large mass 
of materials brought together was almost wholly the work of another 
group of assistants, viz.: J. Douglas Hood, James Zetek, Harry C. 
Severin, and Robert D. Glasgow, and of John A. Grossbeck, of New 
Jersey, assistant at the time to Prof. John B. Smith, of Rutgers Col- 
lege. 


DISCUSSION OF THE SPECIES 


In the following summaries of my data concerning our Illinois 
May-beetles, I have taken the species up in the order of the numbers 
collected, the most abundant species first, and have given for each 
such information as I have concerning their numbers in different years 
in each of the three main divisions of the state, the places from which 
the principal collections were made, the periods of their occurrence 
in the beetle stage, and the plants on which they were taken, with the 
numbers or ratios from each kind of plant. 


Phyllophaga hirticula Knoch 


Hirticula, altho nearly wanting in our northern Illinois collec- 
tions,* is much the most abundant May-beetle in the state, comprising 
nearly 38 percent of all our specimens. Only 81 of our 43,439 speci- 
mens of the species came from northern Illinois, and this is only about 
half of 1 percent of all our May-beetles from that section of the state. 
In central Illinois, on the other hand, nearly 52 percent of our col- 
lections, and in southern Illinois about 14 percent, were of this species. 
In central Illinois, indeed, we found it nearly three times as numerous 





*Among 4,794 May-beetles obtained by J. J. Davis at Galena, in northwestern 
Illinois, May 28 and 31, 1914, were 758 specimens of hirticula. It is possible that 
this central and southern species extends farther north along the Mississippi than 
elsewhere, a supposition consistent with what is said on another page concerning 
the extension of southern species into central [llinois along the watercourses. 


220 BULLETIN No. 186 [ February, 


as the next most abundant species (implicita), and in southern Illinois 
it was surpassed in numbers only by forbesi, for which we made so 
special a search in midsummer that our recorded numbers of it are 
probably disproportionate. This predominance of the species in cen- 
tral Illinois is not due to excessive numbers in any one year, but is 
well marked in four of the six years during which our field work was 
done. While the central Illinois ratios of hirticula for 1907 and 1909 
are only 9.1 and 12.8 percent respectively, those for the four remain- 
ing years range from 56.9 to 70 percent, with an average of 64.7 
percent. 

I do not find in these general data any clue to the life history 
of the species, but this must be found, if anywhere, in the May-beetle 
population of smaller areas than one of the principal divisions of the 
state. Such an examination of our more local data shows us that 
hirticula was not abundant at Urbana in 1906; that it was nowhere 
dominant in 1907; that it was immensely dominant in central Illinois 
generally in 1908, and possibly at Carbondale, in southern Illinois 
also, where 349 of the 1242 of our specimens of Phyllophaga were of 
this species; that it was perhaps subdominant in McLean county in 
1909; that it was strongly dominant in 1910 at Galesburg and dis- 
tinetly so (with inversa) at Urbana (hirticula, 871; inversa, 715), 
and also at Carbondale, at which latter place, however, its numbers 
were approached by micans and vehemens (hirticula, 1813; micans, 
1379; vehemens, 1267) ; and that at Urbana it was strongly dominant 
in 1911, comprising nearly two thirds of the 10,203 specimens col- 
lected there, but followed at some distance by inversa (2107 inversa 
to 6501 of hirticula). As only 102 May-beetles were collected in cen- 
tral Illinois in 1918, the fact that 58 of these belonged to hirticula 
probably has little importance. Its prevalence in central Ilinois in 
1908 and again in 1911 is consistent with the supposition that it has 
a three-year life cycle; but as this apparent periodicity in seasons of 
unusual abundance might well be due to other causes, we are thrown 
back upon breeding experiments for this detail of the life history. 

Our earliest open-air collections of hirticula have been made 
from April 28 to May 10 in different years in central Illinois and 
from April 4 to 18 in southern I]linois, and our latest collections from 
June 30 to July 21 for the central section and from June 17 to 23 
for the southern. The periods of the greatest abundance of the species 
have extended from about the middle of May to the middle of June 
for central Illinois, and from the last of April to the last of May 
for the southern part of the state. 

By following the plow in central Illinois, my field assistants have 
obtained from the ground 822 specimens of hirticula in many fields 
at twenty-six dates between April 6 and June 16, as well as 15 more 
specimens on the 16th of July. The April-June series were probably 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS ° 221 


hibernating beetles which had transformed the year before, but those 
taken in July were most likely newly transformed from pupae of the 
year, not to come up from the ground until the following spring. In 
northern Illinois, where but few collections were made behind the 
plow, one of these beetles was found in the ground April 22, and in 
southern Illinois nine were taken on the same date. 

Quite consistently with its general abundancee, hirticula is a rather 
general feeder. Among the trees and shrubs on which we have found 
it present in large numbers at night are oak, blackberry, mountain 
ash, cherry, hickory, black walnut, persimmon, and bireh—abundantly 
in the order named—, and, in smaller but still considerable numbers, 
gooseberry, linden, poplar, elm, and willow. It has also occurred 
occasionally, and perhaps only accidentally, on apple, plum, box- 
elder, ash, and maple. In a systematic special collection made at 
Urbana May 14 to June 28, 1906, from four food plants only—that 
is, oak, elm, poplar, and willow—342 specimens of hirticula were 
taken, of which 309 were from oak. An examination of my table on 
page 252 will show that this species had a larger percentage of its 
numbers on oaks than twelve of the fourteen other species of that 
table, and a smaller percentage than two. It was, in other words, 
third in the order of apparent preference for the oak; and it was also 
third on the list of hickory species and on blackberry—facts which 
bring it clearly into the oak-hickory group of May-beetles. On the 
other hand, it is sixth on poplar, persimmon, and elm, and thirteenth 
on willow. Its ratios on the other plants of our list are too small to 
serve as indications of its choice of foods. The trees and shrubs which 
it seems to frequent by preference are so numerous and so generally 
distributed in central Illinois that it can scarcely need to go far for 
food from any field in which it may originate, and the effort to poison 
it by spraying its food plants seems therefore practically hopeless. 
It is, on the whole, one of the most dangerous species in the state. 


Phyllophaga wmplicita Horn 


Sixteen thousand nine hundred and eighty specimens of implicita 
are in our Illinois ecollections—nearly 15 percent of our six years’ 
total for the May-beetle genus. This is next to the most abundant 
species in the state, surpassed only by hirticula. Like that species, it 
is relatively poorly represented in the northern part of the state, 
where it made 4.5 percent of our total number of May-beetles for the 
period. In central Illinois, on the other hand, it made 55.5 percent, 
and in southern Illinois, about 10 percent, of those collected in these 
sections. Taken year by year in.central and southern Illinois, we 
find this species making, in 1906, 72.2 percent, and in 1907, 36.6 per- 
cent of the total of our central Illinois collections—virtually all in 
both years from Champaign county; in 1908, 6.1 percent; in 1909, 


222 BULLETIN No. 186 [ February, 


78.8 percent (4541 implicita out of 5758 of all species) ; in 1910, 5.5 
percent; and in 1911, .8 of 1 percent (88 of amplicita in a total of 
10,203). The recurrence of a strongly marked wmplicita year in east- 
central Illinois in 1909, after the great preponderance of the species 
at Urbana in 1906, is consistent with a three-year life cycle for the 
species. In southern [llinois our ratios were: 1907, 3.8 percent; 
1908, 4.4 percent; 1909, 22.2 percent; and 1910, .6 of 1 percent. A 
notable feature of the southern Illinois record is the dominance in 
the south of implicita in 1909, when it was overwhelmingly dominant 
in central Illinois also. 
, Our earliest dates for wmplicita in northern Illinois vary from 
May 20 to 28 in the different years, and our latest, from June 6 to 
25, the period of greatest abundance coming from the last two or 
three days of May to about the 10th or, in one ease, to the 21st of 
June. Our central Illinois dates of earliest appearance range from 
April 27 to May 15, and those of latest occurrence, from June 5 to 
July 1. The time of its greatest abundance commonly fell between the 
last days of May and the middle of June or a little beyond, but in 
the relatively early season of 1906, it came between May 17 and June 
4. In southern Illinois we have found the beetles out as early as April 
21 and as late as July 1, with the month from May 20 and June 21 
as the time when our collections of the species were largest. 

Implicita is unusually definite in its choice of food, being rather 
closely limited to apple, poplar, and willow. Of our 15,724 specimens 
of this species collected from food-plants within our six-year period, 
5107 were from poplar-trees, 4335 from willows, and 4279 from the 
apple—92.5 percent of the whole number from these three kinds of 
trees. The remaining 8.5 percent were divided in only insignificant 
numbers over twenty-four other kinds of trees and shrubs, the largest 
ratios being from oak and elm, 1.5 percent for each. In 1906, when 
2517 specimens of this species were obtained in collections regularly 
made from only four kinds of trees, 2311 of them were from poplars 
and willows, and 206 from oaks and elms. 

The contrast in food habits between this species and hirticula, 
both widespread thruout the state and extraordinarily abundant es- 
pecially in central Illinois, is interesting and suggestive. In the table 
on p. 252, the relative importance to the species of each food-plant is 
shown by the ratio which the number of specimens taken from the 
plant bears to the total number of the species collected from food- 
plants of all descriptions. Since the main features of the food are 
the only ones of any significance in this comparison, ratios of less than 
1 percent are indicated only by a check. From this table it will be 
seen that 30,213 specimens of hirticula and 15,724 of implicita were 
the numbers obtained from food-plants during our six years’ collec- 
tions; that oak and hickory are represented in the food of hirticula 
by 43.6 percent and 18.8 percent respectively, blackberry giving the 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 223 


next largest ratio of 9.2 percent; and that in the ratio for amplicita, 
oak is represented by 1.6 percent and hickory and blackberry by less 
than 1 percent. The principal food resorts of amplicita, on the other 
hand, were apple, poplar, and willow, represented by nearly equal 
ratios and frequented by 92.6 percent of our specimens. The corre- 
sponding ratios for hirticula were poplar, 2.4 percent, willow, 2.9 
percent, and apple, less than 1. It is evident that these species, seem- 
ingly so closely associated over our whole territory, have a different 
ecological distribution, the one frequenting oak and hickory uplands 
primarily, and the other, cottonwood and willow lowlands. 

It seems quite possible that this destructive May-beetle, the sec- 
ond species in the state for abundance, might be effectively poisoned 
by spraying, in May, poplar and willow-trees, if these were so distrib- 
uted and grown over one’s premises as to attract the beetles to them 
and, by regular replacement of old trees by young ones, kept small 
enough to be readily reached with a convenient spraying equipment. 


Phyllophaga fusca Froelich 


Fusca is a distinetly northern species, 43856 of our 11,800 speci- 
mens collected coming from northern Illinois, 7442 from central Illi- 
nois, and but 2 from the southern part of the state, at Carbondale and 
Anna. Within its area it is one of the more abundant species, giving 
us 12.5 percent of the total number of all our collections from the 
northern two thirds of the state. It is one of our earliest May-beetles, 
appearing in 1910 as early as April 9 in central [linois, and in north- 
ern Illinois April 14. It commonly continues numerous to the middle 
of July, its period of adult activity thus covering some three months. 

Our 1907 collections were made chiefly in Champaign county, and 
in McHenry county at Algonquin. In northern Illinois there was no 
indication that 1907 was a fusca year in the districts represented by 
these points. In 1908, however, it was the leading species at Aurora, 
altho futilis crowded it closely for the dominant position. In Cook 
county its numbers, altho small, were nearly double those of futiaes— 
the next most numerous species in our collections of that year. In 
1910 it was subdominant at Aurora and in Cook county, being second 
in both places to anxia. In central Illinois (Urbana and Galesburg) 
it was also subdominant, second only to hirticula, which was, however, 
more than six times as abundant. In 1913 it was dominant at Aurora 
and Rockford, and subdominant in Cook county, where it was ex- 
eeeded by anxia and futilis. Its predominance in Cook county and 
at Aurora in 1910 and again in 19138 indicates a three-year cycle for 
this species. It is a rather indiscriminate feeder, found by us at 
various times in large numbers on apple, ash, blackberry, poplar, and 
walnut. In respect to the ratios of its numbers on its different food- 
plants, it stood first among our species on ash, walnut, hazel, and 


224 BULLETIN No. 186 [ February, 


gooseberry, third on poplar, fourth on elm and blackberry, fifth on 
apple, sixth on hickory and willow, and eighth on oak. It is appar- 
ently the species whose larvae were mainly responsible for the heavy © 
injury to crops in northern Illinois in 1912, as shown by its numbers 
in Davis’s collections there in 1914. It was then the leading species 
in that part of the state, comprising more than 60 percent of the 
13,521 May-beetles obtained by him there that year. 


Phyllophaga inversa Horn 


Inversa is limited to northern and central Illinois, and is espe- 
cially abundant, apparently, in the central part of the state, where it 
made 12.4 percent of all the May-beetles of our collections, as com- 
pared with 8.8 percent in northern Illinois. Curiously, not a speci- 
men of this species was found among the more than 20,000 obtained 
by us in the southern part of the state. In northern Illinois it was 
fifth in point of numbers, being surpassed there by fusca, futilis, 
rugosa, and anxia, while in central Illinois it was the third species, 
only hirticula and implicita being more numerous. 

In 1907 inversa was a dominant May-beetle in Champaign county, 
where it made 27 percent of our collections and was second only to 
implicita (implicita, 6964; aversa, 5157). In 1908 and 1909 we 
found no evidence of its dominance anywhere, our northern Illinois 
material containing only 4 percent of inversa in 1908 and 7 percent 
in 1909; and our central Illinois collections, 2.4 percent and 4 per- 
cent in those years, respectively. In 1910 it was again dominant, with 
hirticula, in Champaign county, 39.7 percent of our collections there 
belonging to hirticula and 32.6 percent to inversa. The same was 
true, however, in 1911, when hirticula contributed 63 percent to our 
Urbana collections (6501 out of 10,203 specimens) and inversa 21 
percent. In 1913 it was apparently a dominant species at Aurora, in 
northern Illinois, second there only to fusca (fusca, 47 percent; in- 
versa, 36.6 percent of our 1940 specimens). 

Our earliest captures of inversa in northern Illinois varied in 
different years from April 15 to May 22 and in central Illinois from 
April 20 to May 9. Its latest occurrences fell between June 21 and 
July 9 in the northern part of the state and between June 13 and 
July 5 in central Illinois. Its periods of greatest abundance ranged 
from the middle of May to the middle of June at the north and from 
about the middle of April to the last of May in central Illinois. 

In respect to its favorite food-plants, inversa differs radically 
from most of our species. It belongs neither in the oak-hickory nor 
in the poplar-willow groups; on the other hand, it is third on our 
list of elm species (anxia, 33 percent from that tree; ilicis, 17.2 per- 
cent; and inversa, 14 percent) ; second of our apple species (implicita, 
32.6, and inversa, 19.6 percent) ; and second also on the blackberry 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 225 


(futilis, 45 percent, and inversa, 22 percent). Its next largest ratio 
was 19 percent on willow, altho it was sixth of the willow May-beetles 
in order of its relative frequency on that plant, and sixth also among 
those taken on poplar. Furthermore, it was first among the small 
numbers collected from the linden, second in the still smaller number 
from hackberry, second also in our 71 collections from the ash, eighth 
from the hickory, and twelfth from oaks. Elm, blackberry, ash, and 
apple seem, from our data, to be its favorite foods. 


Phyllophaga futilis Leconte 


Futilis was one of the moderately numerous species in Illinois 
during our period, its numbers amounting to about 7 percent of all 
our collections. It occurs thruout the state, but we have found it 
jess abundani in southern Ilinois than farther north. This and fusca 
were the dominant or most abundant species at Aurora in 1908, and 
were possibly more distinctly so than at the same place the following 
year, altho our collections of these species in 1909 were too small to 
make this certain. Our data are not so distributed in time as to give 
us any information concerning the length of life of the generation. 
This is a rather early spring species, sometimes appearing even in 
northern Illinois by the middle of April and in southern Ilinois be- 
fore the end of March. It is also rather long-continued, not disap- 
pearing as a rule in the central part of the state until July is well 
advanced. Among the 1650 collections of May-beetles from the 45 
food-plants which yielded our specimens, we found futilis in any 
considerable number only on blackberry, apple, hackberry, elm, and 
eorn; but, curiously, 73 of 102 specimens from the four food-plants 
in 1906 were from poplars. Sixteen hundred and thirteen of our 
specimens were taken in 88 collections from blackberry bushes, and 
331 in 58 collections from apple-trees. A larger proportion of futilis 
than of any other species was taken from blackberry. In our list of the 
fifteen most important May-beetles it stood first, also, on hackberry 
and corn, second on elm, box-elder, birch, honey-locust, and goose- 
berry, fourth on apple, ninth on willow, and thirteenth on oak. Its 
numbers on ash, hickory, and poplar were each less than 1 percent 
of the whole number of the species obtained from food-plants. The 
collections from corn were made in a field which had been heavily 
infested by white-grubs the year before, and the beetles, coming out 
of the ground in early spring during a cool wet time, fed freely on 
the young corn, to its considerable injury, without leaving the field. 

Futilis was evidently one of the species responsible for very heavy 
erop injuries by white-grubs in northern Illinois in 1912, as shown 
by its numbers there in 1914, when it yielded more than 17 percent 
of all the northern Illinois collections contributed by Davis. 


226 BULLETIN No. 186 [ February, 


Phyllophaga forbest Glasgow 


Forbest is a species recently described,* hitherto frequently con- 
fused with ephilida Say. It is abundant in southern Illinois, and has 
a considerable additional range in the Southern States. It was ob- 
tained by us first at lights in Odin, Marion county, May 21, 1908, and 
also June 21 of the same year at Thebes, Alexander county, again at 
lights, and August 10 from the ground in collections made by follow- 
ing the plow. A special search was begun for it in 1909 with the 
result that 2766 specimens were obtained at Odin, Olney, Ashley, 
Carbondale, and Anna, the earliest May 21 and the latest August 6. 
It was most abundant from June 17 thru July to early August. In 
1910, 602 additional specimens were collected, July 21 to 25, at Patoka 
in Marion county and at Carbondale, and 13 were taken July 21 at 
Urbana, the northernmost point at which the species has been found. 

In 1911 an attempt was made to ascertain the limits of its dis- 
tribution northward, with the result that 352 specimens (which have 
not been included in my tabulations or summaries) were collected 
July 27 to August 6 at Centralia, Odin, and Kinmundy in Marion 
county, at Effingham in Effingham county, at Greenville in Bond 
county, and at Ramsey in Fayette county, but none were found at 
Taylorville, Pana, Mattoon, Charleston, Neoga, or Litchfield. 

The food of forbes: has proved to be as peculiar as its late sea- 
sonal period. Of our 2088 specimens collected from their food-plants, 
852 were from cherry-trees, 463 from peach, 422 from apple, 29 from 
persimmon, and 15 from plum—1781 specimens, or 85 percent of the 
whole, from these various fruit-trees. Except for 58 specimens from 
the rose, the remaining 15 percent were scattered in small numbers 
over sycamore-, walnut-, elm-, oak-, hickory-, and willow-trees. It is 
thus essentially a cherry, peach, and apple species, at least in Illinois. 
Its larva has not been identified by us, and nothing is known to me 
of its life history. 


Phyllophaga rugosa Melsheimer 


Rugosa is essentially a northern species in Illinois, 84 percent of 
our 2769 specimens having come from northern Illinois, 14.8 percent 
from central, and only 1.2 percent from the southern part of the state. 
This was, indeed, the dominant species in northeastern Illinois in 
1907, if we may judge by collections from lights made at Algonquin, 
McHenry county, from June 14 to July 16, 67 percent of our speci- 
mens taken there at that time belonging to rugosa. It was subdomi- 
nant the following year in Cook and Kane counties, when it was sur- 
passed only by fusca (fusca, 35.2 percent; rugosa, 18.9 percent), but 
in the three following years and in 1913 it dropped away to insig- 
nificant numbers in our northern Illinois collections—to 7 percent in 


*Bull. Tl. State Lab. Nat. Hist., Art. V, Vol. XI, p. 378. 


1916) MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 227 


1909 and 1 percent or less in 1910, 1911, and 19138. That this decline 
was not local merely, is shown by the fact that it affected our numbers 
for central Illinois also, which fell from 841 specimens in 1908 to 15 
in 1909, to 5 in 1910, to 3 in 1911, and to none at all in 1913. 

Rugosa is very scarce in Davis’s northern Illinois collections made 
in 1914, and it evidently had no share in the extensive injury done 
to crops thruout northern [Illinois by white-grubs in 1912. 

It is a late species in its seasonal appearance, our earliest col- 
lections in northern Illinois coming from May 25 to June 14, and those 
in central Illinois from May 15 to June 12. 

It stands first on our list of poplar species, and second among 
those from willow, where it is surpassed only by bipartita. Seventy- 
one percent of our specimens of rugosa collected from food-plants 
came, in fact, from these two trees. It is eighth on our list from the 
oak and fourth on that from the blackberry. Of 200 specimens ob- 
tained in systematic work on oaks, elms, poplars, and willows, in 1906, 
169 were taken on poplars and the remainder on elms. This is ap- 
parently a species of minor economic importance. 


Phyllophaga micans Knoch 


Micans is a persimmon-oak May-beetle with distinctly southern 
distribution, 2671 of our 2700 specimens having come from that part 
of the state, with 10 from central and 19 from northern Illinois, the 
last from Aurora and stations about Chicago. In southern Illinois it 
is a common species, third in order of abundance there, and making 
13.3 percent of all our collections from that section. It was, indeed, 
our dominant species there in 1907 and 1908, fourth in abundance in 
1909, and second in 1910. Our earliest southern Illinois dates for its 
occurrence are April 4 and 18, and our latest are June 80 and July 12. 

Eighty-five percent of the 1431 specimens collected from food- 
plants came from persimmon- and oak-trees—50.7 percent from the 
former and 34.2 from the latter. Indeed if we take account of the 
larger number of collections made from oaks than from persimmons 
in southern Illinois, and adjust our ratios accordingly, we find that 
about four times as many of these beetles would have been obtained 
from persimmons as from oaks if equal numbers of these kinds of 
trees had been taken. Muicans thus seems to be essentially a persimmon 
species. 

Phyllophaga anxia Leconte 


Anxia (formerly known as dubia) is almost as distinctly a north- 
ern species as micans is a southern one, 1959 of our 2116 specimens 
coming from the northern part of the state, 82 from central Illinois, 
and 75 from southern. Five hundred and ninety-three of these beetles 
were obtained, however, in 1911 and 1913, when we made no southern 
Illinois collections; and after subtracting these, the ratios for the 


228 BULLETIN No. 186 [ February, 


remaining years are 90 percent for northern Illinois and 5 percent 
for each of the other divisions of the state. The species was dominant 
in northern Illinois in 1910, when it gave us 36.9 percent of all our 
northern Illinois May-beetles, the one next in abundance (fusca) giv- 
ing us 22.9 percent. Anzia was subdominant at the north in 19138, 
when it was exceeded only by fusca and inversa. It is apparently a 
three-year species. In the year of greatest abundance, 1910, it was 
first collected by us in northern Illinois April 15 and last occurred 
there June 30, its greatest numbers falling between May 16 and June 
16. It was taken by us, however, in that part of the state as late as 
July 8. 

In respect to its food, as shown by 1244 specimens obtained by us 
from food-plants, it is peculiar in the combination of a preference for 
elm and willow. It is, in fact, first on our list of species from the elm, 
in respect of course to its proportionate numbers on that tree. It is 
fourth on our willow series, and fourth also on our series from the 
poplar. It is thus essentially a willow-poplar species, with a further 
exceptional preference for the elm. It was sixth on our list from 
the apple, third on the cherry, third on the box-elder also, first on 
the hackberry, second on the linden and the mountain ash, and tenth 
on the oak. Three fourths of our specimens came, however, from the 
elm, willow, poplar, and apple. 


Phyllophaga bipartita Horn 


Bipartita is a southern Illinois species, only 6 of our 1725 speci- 
mens coming from central Illinois and none at all from northern. 
Urbana is at present our northernmost point for the species in this 
state. In 1907 and 1908 its numbers were very small, only 2 speci- 
mens in the former and 46 in the latter, but in 1909, 797 were taken 
and in 1910, 850, all in both years from a number of stations in south- 
ern Illinois, Olney and Odin the northernmost and Carbondale the 
farthest south. Its seasonal range was best shown in 1910 when our 
earliest specimens were taken April 15 and our latest June 30. This 
is primarily a willow species, 86 percent of our 645 specimens from 
food-plants coming from willows. It has also some tendency to hick- 
ory and oak, these two together yielding 12.2 percent additional. The 
small numbers remaining were found only on persimmon and apple. 


Phyllophaga fraterna Harris 


Fraterna is another southern species with a very sparse distri- 
bution north as far as Chicago. There were 1512 specimens in our 
six years’ product, all but 64 of them from southern Illinois. Fifty- 
eight came from various points across the state between Danville and 
Galesburg, and 6 from Aurora, Edgebrook, and Calvary, in Kane and 
Cook counties. Our earliest date in any year was March 28 in 1908, 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 229 


and our latest was July 8, also in 1908. Fraterna is one of the oak- 
hickory-persimmon species, especially characteristic of southern Il]li- 
nois, these three kinds of trees giving us 95 percent of our specimens. 
Three and five tenths percent came from willows, and a very few from 
poplars and black walnuts. 


Phyllophaga profunda Blanchard 


Profunda is strictly confined to southern Illinois, all our 1336 
specimens coming from that section except one from Hoopeston, in 
Vermilion county. This species was especially abundant in the south 
in 1910, when it made 11 percent of our collections there, being sur- 
passed in numbers only by hirticula, micans, and vehemens. It was 
first taken that year on April 9, and for the last time July 21. All 
but scattering specimens, however, came between May 2 and 26. It 
is to a marked degree an oak-hickory species, 90 percent of our 1085 
specimens coming from these two kinds of trees, and another 7 per- 
cent from the persimmon. 


Phyllophaga tristis Fabricius 


Tristis, nowhere very abundant in our collections, is one of the 
May-beetles most closely limited to a single food-plant, being essen- 
tially an oak species. Sixteen hundred and thirty-four specimens 
were obtained in 130 collections from oak—an average of 9.6 to the 
collection—only 131 specimens coming from other food-plants, of 
which hickory was the most important. Nevertheless, it appears from 
our data that if equal numbers of collections had been made from 
hickory and oak, the specimens from hickory would have numbered 
only 3.4 percent of those from oak. Notwithstanding this controlling 
preference for oak leaves as food, only about 9 percent of the Phyl- 
lophaga specimens obtained from oaks belonged to this species. 

Tristis was obtained thruout the state in collections ranging from 
Cook to Union counties, numbering 523, 1037, and 324 in those from 
northern, central, and southern Illinois respectively. 

It was curiously limited, however, in its local occurrence, all our 
specimens from oaks coming from Aurora, Galesburg, Anna, and Car- 
bondale, while large collections made in the same years from these 
trees in McLean and Champaign counties and small collections from 
Cook and Perry counties, did not give us a specimen of this species. 
It was taken infrequently at lights, only 191 specimens of it occurring 
among 29,752 May-beetles obtained by us from lights and light-traps; 
and these small miscellaneous collections were distributed like those 
from their food-plants, except that 24 specimens came from Danville, 
in Vermilion county, on the eastern border of the state. Evidently 
the distribution of this species is restricted by ecological conditions 
other than those connected with latitude and food. 


230 BULLETIN No. 186 [ February, 


It seems to be a rather early species, occurring in our southern 
Illinois collections from March 28 to June 21, in central Illinois from 
May 2 to July 2, and in northern Illinois from May 16 to July 2. Our 
data of local abundance in different years are not sufficient to give us 
any definite clue to the length of its life cycle. 

Altho the preference of this species for oaks, and the well-known 
greater injury done by white-grubs to crops growing near forest trees, 
might lead us to give to it an unusual economic consequence, its num- 
bers are apparently so small that it does not seem likely to do any 
considerable general injury in any stage. 


Phyllophaga ilicis Knoch 


Ilicts is a minor species represented here by only 873 specimens 
which is less than 1 per cent of the grand total of our collections. It 
is distributed thruout the state, but seems somewhat the most abun- 
dant in northern Illinois, where it amounted to nearly 4 percent of 
our whole number collected. It was, indeed, dominant in the northern 
section, together with futilis, in 1909, making 27 percent of our 2073 
northern Illinois specimens for that year to 37 percent of futilis. It 
is a comparatively late species to appear in spring, our earliest cap- 
tures coming between May 2 and 26 and our latest between June 16 
and July 18. 

It is a rather general feeder, with a marked preference, however, 
for oaks. It is, in fact, the third of our fifteen principal May-beetles 
in the size of its ratios on oaks, greatly surpassed by trastis and a trifle 
only by hirticula, but very nearly equalled by fervida and fraterna. 
Its next strongest preference seems to be for elm, in respect to which 
it is second only to anzia (anxia, 33 percent; alicis, 17.2 percent). 
On the other hand, its numbers on poplar and willow, altho relatively 
small, were too large to be merely accidental. In the four-food-plant 
series of 1906, 317 out of 3851 specimens were from oaks, and 21 from 
elms. It was eighth in order of our willow beetles and fifth of those 
from poplar. It was sixth on blackberry, fourth on ash and black 
walnut, and second on hazel, hawthorn, and rose. Plum, persimmon, 
linden, honey-locust, gooseberry, birch, and apple each yielded a few, 
perhaps merely accidental visitors. 


Phyllophaga fervida Fabricius 


Fervida, better known under its synonym of arcuata, is a south- 
ern and central species, only one of our 857 specimens coming from 
northern Illinois. It was furthermore some fifteen times as numerous 
in southern Illinois as in central, due account being taken of the dif- 
ferent numbers of our total collections from these two sections. It 
was proportionately much more abundant at the south in 1910 than 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 231 


in any other of our collection years, but was, nevertheless, even then 
only fifth among our southern Illinois species in frequency of occur- 
rence. There is nothing peculiar in the seasonal dates of this species. 
Our earliest southern Illinois captures were made between March 28 
and April 17, and our latest from the middle to the last of June. 
With respect to its food it is ike many other southern species—an oak- 
hickory-persimmon May-beetle, 88 percent of our specimens having 
been taken from these trees. Some 10 percent from willows and 2 
percent from ash account for the small remainder. 


Phyllophaga vehemens Horn 


Vehemens, represented by 1426 specimens, is a typical southern 
species in Illinois, only 21 coming from central and none from north- 
ern Illinois. The central Illinois specimens were collected in Macon 
and McLean counties in 1907, 1908, and 1909; in southern Illinois 
we have taken the species at many points from Belleville to Shawnee- 
town and Cairo. All but 36 of our specimens were collected at lights, 
and we have no sufficient data for a discussion of the food of the 
species. About nine tenths of our vehemens collection was obtained 
at Carbondale in 1910, mainly between March 27 and April 15, addi- 
tional scattering specimens occurring up to May 24. This seems to be 
the earliest in spring of all our May-beetles, altho occasional captures 
of it have been made by us up to July 1. Vehemens was among the 
dominant species in southern Illinois in 1910, where it was exceeded 
only by lirticula and micans, but its numbers in the three other years 
of our southern Illinois collections have been but few. Its food, as 
already remarked, is practically unknown. 


The foregoing sixteen species are represented by 112,118 speci- 
mens, thus amounting to nearly 98 percent of our Illinois collections. 
The remaining eighteen species are represented by only 2356 specimens 
in all—too few to give their numbers any important ecological or 
economic significance. It seems, nevertheless, incumbent upon me to 
report such facts as the record contains, as hints or clues which may 
be of use to other entomologists. These remaining species will be 
treated, like those preceding, in the order of their numbers in our 
collections. 


Phyllophaga crenulata Froelich 


Crenulata was represented by 630 specimens, 503 of which were 
from southern, 73 from central, and 54 from northern Illinois. It is 
thus distinctly a southern species, as is most clearly seen from the 
ratios of its numbers in each section of the state to the total for the 
state as a whole. These are, respectively, 79.8 percent for southern, 
11.6 percent for central, and 8.6 percent for northern Illinois. It 


ee, BULLETIN No. 186 [February, 


showed, during the years covered by our southern Illinois collections, 
no conspicuous fluctuations in abundance. So far as we may judge 
from the 255 specimens collected from plants, crenulata seems to be 
a persimmon species, with willow and hickory as second choices. One 
hundred and five of our specimens (41 percent) were taken from per- 
simmon trees, 41 (16 percent) from willows, and 25 (10 percent) from 
hickory—two thirds of our little collection from these three trees. A 
unique additional feature is the occurrence of 22 specimens in four 
collections from poison ivy. Elm, grape, and hackberry are repre- 
sented by small numbers, and oak by still smaller. 


Phyllophaga corrosa Leconte 


Corrosa is represented by 476 specimens, only 1 of which was 
from northern Illinois, all the rest coming from the southern part of 
the state. The earliest date of capture was April 9 in 1910, and the 
latest, July 2, in 1907. Ninety-five specimens taken from food-plants 
show that corrosa is clearly an oak-hickory-persimmon species, with 
persimmon apparently preponderating as food. All the specimens 
were taken from these plants except 2 from blackberry. 


Phyllophaga draku Kirby 


Drakuw, commonly labeled grandis in collections, is northern in its 
Illinois distribution, only 8 of our 429 specimens having come from 
the southern part of the state. Its increasing abundance northward 
is shown by the fact that our central Illinois collections amount to 
less than 2 percent of our total for that part of the state, while those 
for northern Illinois were nearly 18 percent of the northern Illinois 
total. 

This species is evidently late in appearance, our earliest dates 
generally coming from the middle to the end of May. We have, how- 
ever, one capture made April 21 in central Illinois, and another May 
2 in the southern part of the state. Our latest specimens were ob- 
tained from the middle to the end of June, with the exception of one 
on July 7. 

The food of draki seems to be highly composite, if we may judge 
from our 378 specimens collected from trees and shrubs. The species 
was taken most frequently on willow, poplar, oak, elm, hazel, and 
blackberry, in ratios diminishing from 20 percent on willow to 13.5 
pereent on elm and 9.8 percent on blackberry, the total for these seven 
plants being 86.4 percent. Other plants resorted to, by small num- 
bers of the beetles, were rose, ash, gooseberry, mountain ash, birch, 
honey-locust, raspberry, apple, hawthorn, plum, box-elder, and Vi- 
burnum. 


WwW 
iss) 
ie) 


1916 | MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 


Phyllophaga congrua Leconte 


Congrua is also a species of somewhat general distribution in the 
state, with a strong tendency southward, however, where 175 of our 
190 specimens were captured in 1907, 1908, and 1909. In two of 
these years, indeed, none were taken-outside of southern Illinois. In 
the third year, fourteen came from northern Illinois and one from 
central. Our dates of occurrence range from May 12 to July 7. Our 
notes on the food-plants of the species are limited to 66 specimens, 65 
of which were obtained from willows and 1 from the oak. 


Phyllophaga crassissima Blanchard 


One hundred and sixty-five specimens of crassissima were col- 
lected in central and southern Illinois during the four years 1907 to 
1910, at dates ranging from May 21 to June 28. All came from lights 
except 1, taken April 6 behind a plow, and 10 from various plants— 
in numbers quite too small to give us any useful hint of the food of 
the species. 

Phyllophaga delata Horn 


Delata is apparently a southern species, all our 106 specimens 
having come from southern Illinois in 1908, 1909, and 1910. The 
earliest date of collection was April 15 and the latest June 30, both 
in 1910. Altho we obtained but 29 specimens from food-plants, the 
fact that 16 of these came from hickories, 12 from oaks, and 1 from 
the persimmon, seems sufficient evidence that this is an oak-hickory 
species. 

Phyllophaga mtida Leconte 


Our specimens of nitida are only 76, all from northern Illinois 
in 1907 and 1908. Seventy-five of these were taken at Aurora in the 
latter year, 73 of them from hazel bushes, and 2 from lights. Our 
only other specimen was from Algonquin, in McHenry county, July 
6. The Aurora specimens were captured at various dates from May 
25 to June 9. 


Phyllophaga forstert Burmeister 


Forsteri, for which nova is a synonym, is represented with us by 
70 specimens, of which 60 were southern, 1 central, and 9 northern 
in this state. It was taken in each of the first four years of our period 
at dates ranging from May 18 to June 18. Sixty-two of the 70 were 
collected from food-plants, 42 of them from oaks, 12 from hickories, 
7 from persimmons, and 1 from the willow, a clear indication that 
this is one of the oak-hickory-persimmon group of the southern part 
of the state. 


234 BULLETIN No. 186 [ February, 


Phyllophaga horns Smith 


Horm was obtained by us only from central Illinois in the years 
1908 and 1909, 64 specimens in the first year and 2 in the second, 
from May 17 to June 21. Forty-six of our specimens were from food- 
plants, 36 of these from blackberries, 4 from oaks, 2 from poplars, 1 
from willow, 2 from cherry, and 1 from elm. 


Phyllophaga praetermissa Horn 


Praetermissa is apparently a distinctly southern species, repre- 
sented, it is true, in our materials by 55 specimens only, but all of 
these coming in three different years from the southern part of the 
state at dates ranging from May 14 to June 22. They were well dis- 
tributed from Odin, Ashley, and Duquoin to Shawneetown on the 
Ohio. Only 26 of our specimens were from food-plants, 18 of them 
from oak, 9 from willow, and 4 from apple. 


Phyllophaga prunina Leconte 


Prunina is represented by small seattering collections made dur- 
ing three years in all parts of the state and amounting to only 33 
specimens. The fact that 3 were from oaks and 1 from hickory gives 
us only a hint of the probable character of its food. 

Prunina was surprisingly abundant among May-beetles collected 
near Chicago for Mr. J. J. Davis in 1914, where 2142 of this species 
were taken in a total of 16,550. I am informed by Mr.. Davis that 
this is characteristically a species of sandy situations, a fact which 
will account for its general scarcity in Illinois. 


Phyllophaga longitarsa Say 


Longitarsa, represented with us by 15 specimens, was taken only 
at lights in Grand Tower, Jackson county, July 12, 1909. We have 
thus no hint of the character of its food. 


Phyllophaga arkansana Schaeffer 
Arkansana was represented by a single collection of 11 specimens 
taken from lights at Ashley, Washington county, May 4, 1908. 
Phyllophaga villifrons Leconte 


Our 9 specimens of villifrons came from northern and central 
Illinois, 8 from lights at Algonquin, June 14 to July 8, and 1 from 
an oak at Galesburg, June 4. 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 235 


Phyllophaga balia Say 


We obtained but eight specimens of balia, all from the northern 
and central sections of the state at various dates between April 28 and 
June 8. They were from birch, hazel, apple, and gooseberry, but in 
numbers too small to give any definite indication of the food of the 
species. 

Phyllophaga barda Horn 


Our 5 specimens of barda, obtained from April 25 to May 26, 
1908, at Danville, Carbondale, and Anna, in central and southern 
Illinois, were all from lights. 


Phyllophaga calceata Horn 


Calceata was obtained by us only in 1907, 2 specimens from the 
central part of the state and 8 from the southern part, May 22 to 
June 27, all at lights. 


Phyllophaga lirtiventris Horn 


Hirtiventris is represented by but 2 specimens from Metropolis, 
on the Ohio River. They were obtained from lights June 22, 1908. 


The foregoing accounts for all our collections of the years men- 
tioned, except some twenty specimens not yet satisfactorily determined. 


THE SPECIES BY SECTIONS OF THE STATE 


Northern Illinois Species—In northern Illinois there were but 
three species, rugosa, anxia, and nitida, so far limited to that section 
that they may properly be called northern species. Rugosa yielded 
us from northern Illinois 2326 specimens out of 15,457 of all species 
collected there, 410 specimens out of 78,916 from central Illinois, and 
33 out of 20,120 from southern Illinois—numbers equivalent to 15 
percent, .52 of 1 percent, and .16 of 1 percent from the three sections, 
respectively. As a poplar-willow species its ecological affiliations lie 
northward rather than southward, but its food-plants are common 
enough, at least along watercourses, in central and southern Illinois 
to permit its extension into those areas. Anwxia, a May-beetle of di- 
versified food habits, distinguished by its preference for elm but other- 
wise mainly a willow-poplar species, occurs thruout the state, but it 
gives from northern Illinois a percentage of specimens a hundred and 
twenty-seven times as large as that from central Illinois and over 
forty times as large as that from southern Illinois; that is, our north- 
ern Illinois collections of anxia were 12.7 percent of the total number 
of May-beetles there, and the corresponding ratios for the other two 
sections were .1 of 1 percent for the central and .37 of 1 percent for 


236 BULLETIN No. 186 [February, 


the southern sections. Nitida seems even more distinctly northern, if 
we may judge from our small collections, entirely from Aurora and 
Algonquin, and nearly all from hazel thickets in the forest border. 

Northern-Central Species——Three of our May-beetles, fusca, in- 
versa, and draki, altho most abundant northward and virtually ab- 
sent from southern Illinois, are sufficiently at home in the central 
district to warrant our grouping them as northern and central species. 
Fusca, for example, which gave us 28.2 percent of all our northern 
Illinois May-beetles, yielded also 9.4 percent of those from central 
Illinois, but virtually none from farther south. The corresponding 
ratios for inversa were 8.8 percent northern, 12.4 percent central, and 
none southern; and for the much less abundant drakiu they were 1.8 
percent, .18 of 1 percent and .04 of 1 percent respectively. Otherwise 
stated, for each 1000 of drakuw taken in northern Illinois we might 
expect, in an equal number of similar collections, 100 from the central 
part of the state and 2 or 3 from the southern. What physiological 
or ecological conditions limit the distribution of these species south- 
ward it is impossible to tell without much more detailed and intensive 
ecological work than has thus far been attempted by us. We may 
only note that all three of these species have a diversified food habit, 
and belong to neither of the great groups of poplar-willow or oak- 
hickory-persimmon species. 

Central-Southern Species.—Two of our species, hirticula and 
fervida, common to central and southern Illinois, are nearly wanting 
to the northern part of the state. Hirticula, a decidedly general 
feeder with an apparent preference for oak and hickory, has a much 
larger representation in southern Illinois than in central, making 
more than half our total collections in the former and less than 15 
percent in the latter. Its numbers in northern Illinois we found quite 
insignificant; altho 11.6 percent of the Galena May-beetles collected 
by Davis in 1914 were of this species. Fervida, on the other hand, 
was much more distinctively southern, giving us 3.4 percent of our 
southern Illinois May-beetles and a little over 1 percent of those from 
central Illinois, with only a single specimen from farther north. It is 
an oak-hickory-persimmon species. 

Southern Illinois Species—The eleven properly southern [lli- 
nois May-beetles are all species of the southern states which find their 
northern limit in the southern part of Illinois. They are a fairly 
uniform group in respect to their food, as is shown by the following 
list of their principal food-plants. 

Bipartita: willow, hickory, oak. 

Corrosa: persimmon, oak, hickory. 

Crenulata: persimmon, willow, hickory. 

Delata: oak, hickory. 

Forbesi: cherry, peach, apple. 

Forsteri: oak, hickory, persimmon. 


1916 | MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 237 


Fraterna: oak, hickory, persimmon. 
Micans: persimmon, oak. 
Praetermissa: oak, willow, apple. 
Profunda: oak, hickory, persimmon. 
Vehemens: food unknown. 


COMPARISON OF THE SECTIONS OF THE STATE 


The greater diversity of surface and variety of ecological situa- 
tion shown in southern Illinois, with its level prairies of gray silt 
loam to the north changing gradually into the broken country of the 
Ozark hills at the south, bordered on the west by the broad bottom- 
lands of the Mississippi and on the south by the Ohio, create local 
conditions whose wide diversities are reflected in the various composi- 
tion and ratios of their insect inhabitants. Central Illinois, on the 
other hand, has a much more monotonous topography and a May- 
beetle population more uniformly distributed. Our May-beetles from 
Anna in the years 1908 and 1909 were much less like those from 
Carbondale, only seventeen miles away, than were those of Galesburg 
like those at Urbana, a hundred and twenty-four miles apart but both 
in the central Illinois prairie region. The five most abundant species 
in 1908 were the same at the latter two towns, differing only slightly 
in the order of their numbers, which amounted, at each place, to 99 
percent of the May-beetles collected at these points in that year; while 
in southern Illinois only two of the five most abundant species at 
Carbondale and Anna were common to both lists. The first and sec- 
ond of the Anna list were ninth and tenth of the Carbondale list, the 
third at Anna was the second at Carbondale; the fourth was the first, 
and the fifth was the fourteenth. 

Looking in some detail at the extension of distinctively southern 
species into central Illinois, we find that it is especially notable at 
points where central Illinois streams are bordered by broken wood- 
lands—where, in other words, the ecological conditions approach those 
of the hill country of the southern part of the state. Danville on the 
Vermilion, Decatur on the Sangamon, and Havana on the Illinois, are 
such locations, and here southern species were taken in 1907 and 1908 
as follows: at Danville, crenulata, forsteri, fraterna, and vehemens; 
at Decatur, crenulata and vehemens; and at Havana, crenulata, and 
micans,—five of the eleven mainly southern species at one or more of 
these central Illinois points. The real boundaries of our areas of dis- 
tribution are, of course, not the artificial lines separating the con- 
ventional sections of the state, but they run a highly irregular course, 
their meanderings guided largely by the location of our streams. 
The southern species are, however, represented, as a rule, in central 
and northern :I]linois by numbers so small that they can cut no figure 
in the general mass of the May-beetle population of the central and 


238 BULLETIN No. 186 [February, 


northern parts of the state, and are hence of little or no economic 
interest there. 
COMPARATIVE COLLECTIONS AT LIGHTS, 


CENTRAL AND SOUTHERN ILLINOIS, 
1907 AND 1908 


















































| a = 
© w 3 be sy 4 
. = asl fae} & 3 8 
Species = i ave 2 = = A 8 = 
a S >oO q = 3° 2 + SH 
oS 0) a A we AS © : 
. oe) a aries < oO pq 6 |m 
AVIZIR OF. cote ee eee vl 0 0 0 0 1 0 | N. 
Bards ai. ve Serie eas 2 0 0 2 i 0 0 | CS. 
Bipartitacceicic. coc ease 0 0 0 0 9 0 er pest 
Caleestal or. (sa. ee 0 0 2 0 0 0 0| 8. 
LIOUOPIS eras ho tee 0 0 0 16 0 0 ie t= 
COrrosa.tc ed ooo eee eee 0 0 0 0 123 0 0 in 
Craasissinigaw sin eee 0 0 4 0 0 0: 0 | C.S. 
CTanuiatehe ue. esis eaten 56 His ah | 0 105 0 0 }.82 
Delatasr ce ee 0 0 0 0 3 0 022: 
Dirgkhi oars Cl ee ee a: 0 0 0 0 2 0 | N.C. 
Wervidnd Aa ret aoe. 139 0 0 0 Bo 0 0 | C.S. 
TLOTSUOTES Hoo ees ieee te oe 1 0 0 0 1 0 0/8. 
HRraternis, soccer 1 0 0 2 52 0 0 |S. 
Musca soe ene es Oe ee 187 97 0 0 0 97 40 | N.C. 
Wivtitis: Stags eee 79 35 0 181 32 9 37 | Gen. 
Hirticula. 77 eee 591} 198 | 21 48 340| 386 | 235 | C.S. 
Horns ois boa ee oe 12 0 0 0 | 0 5 0 | ? 
Tieis 2 4 shee eee ae 23 0 1 23 5 0 2 | Gen. 
Impligitacns arene ee 195 8 3 9 35.| 129 29 | CS. 
Pnveres.. ss ce ee See ee 79 0 0 0 0 99 30 | N.C. 
Micans fl celine ee ee 0 0 9 19 Oke 0 0/898. 
Peosundas be oe pee eee ee 0 0 0 0 87 0 0.183 
RU POSS qe sate ae eee 200 35 5 0 2 3 Lie; 
EU PIStIS Veet eae ee me ee, 24 ii 0 8 12 0 7 | Gen 
Wighemens ens oe cree eee He 15 0 0 66 0 0/8. 
Totals.) thet Ree 1,616| 390 | 56 | 306 |1,225| 731 | 391 





We notice a much greater similarity of food habit in the southern 
species than in the northern—oak, hickory, and persimmon being the 
principal elements of the food of eight of the ten such species whose 
food we know, the ninth being the peculiar fruit-tree species forbes, 
and the eleventh, vehemens, which we have taken only at lights. 
Furthermore, fervida and hirticula, which are southern and central 
species, are both oak-hickory May-beetles, fervida being especially 
common on persimmon also. The four northern and central species, 
on the other hand, alicis, fusca, inversa, and drakii, are all of a differ- 
ent food habit from the foregoing group, ilicis most abundant on oak 
and elm, fusca and drakw rather general feeders, and inversa espe- 
cially abundant on the willow, elm, and hickory. 


239 


ETLES (PHYLLOPHAGA) OF ILLINOIS 


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940 BULLETIN No. 186 [ February, 


SEASONAL SUCCESSION OF THE SPECIES 


That the different species of May-beetles do not make their first 
appearance on the wing in spring at the same time is a fact familiar 
to all collectors, but the actual order of their succession is not easy 
of determination. Species rare in any locality are much less likely 
than abundant ones to be taken at the very beginning of their period 
of activity; even the same species, may seem, consequently, to differ 
in position in the seasonal list in different years according as it is 
relatively abundant or relatively scarce; the position of a species in 
the seasonal list may differ in different parts of the state, since the 
assemblage of species themselves will be different; a species sensitive 
to cold may be relatively early in the south and yet relatively late in 
the north, where its activities are restrained by too low a temperature; 
an apparent difference of date between two species may be due to the 
fact that collections were not made from their respective food-plants 
at the same times; if collections from lights are depended on, it may 
easily happen that the distances from these lights to the places where 
the different May-beetles breed and emerge most abundantly or to the 
food-plants on which the different species assemble, are widely differ- 
ent; or the abundance of these food-plants in the neighborhood of the 
lights may differ so widely that, of equally common species, some may 
appear in collections abundantly and early and others sparingly and 
late; the various weather of different seasons and of different parts 
of the same season may have its disturbing influence; and finally, in 
our case, these differences of successive years in respect to the distri- 
bution of our collections in time, space, and food-plants must have 
introduced differences in succession which are artificial and apparent 
only. The subject is, nevertheless, sufficiently important to those who 
would understand the economy of our May-beetle population to make 
it worthy of careful inquiry. 

For this purpose I have prepared tables showing the precise dates 
on which all our dated collections of each species were made, in each 
part of the state and in each of the four years from 1907 to 1910 
inclusive, the species of each table being arranged substantially in the 
order of their first appearances in spring. In a few cases this order 
has been slightly changed where the mass of one species appeared 
earlier than that of another, even tho the first collections of the latter 
might have antedated a little those of the former. By a comparative 
study of these seasonal tables, all necessary allowances being made for 
differences in abundance of the various species in the collections of 
each year, it seems possible to arrive at a fairly correct idea of the 
normal order of succession of the more important kinds of May-beetles 
for northern, central, and southern Illinois respectively—the succes- 
sion which would be exhibited if collections were sufficiently numerous 
and so distributed in space and time as to draw at each collection in 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 241 


equal ratios from all the species. As the product of such a comparison 
and adjustment, we may take the following numerical lists of the 
principal species of each section collected in each year, and the final 
comprehensive lists showing approximately their general order of 
succession. These latter lists represent 98 percent or more of the total 
number of May-beetles from each part of the state. The arrangement 
of species in the northern and central Illinois lists seems plausibly 
valid, but the adjustment of the list for southern Illinois is a much 
more difficult matter, and I am less confident of my success in es- 
tablishing the correct chronological order there, especially as the or- 
dinal relations of some of the species of the southern list seem different 
from those of the same species in the list for central Illinois. More 
reliable data upon this subject might be obtained by general nightly 
collections made from the very beginning of the season over a con- 
siderable area in one or more localities for each section of the state; 
but until this can be done the following may be accepted as the best 
practicable with my materials. 


SUCCESSION OF SPECIES IN NORTHERN ILLINOIS 



































1907 1908 1909 1910 

n n —— wD n 
Ore, Dawn On ow 

Dm Q2gibn 2Qalh 2Qeaib 2 
a8 a Slas asia glo 3 a8 
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i fusea 2 1 | fusea iL 1 | anxia 6 1 | fusea A 
2 anxia 5 2 | anxia 6 1 | fusca a 2 | anxia Pel 
3 rugosa 1 3 | futilis 2 3 | tristis 3 3 | inversa 6 
4 ilicis RB 4 | inversa 5 4 | inversa 4 4 | tristis 8 
a futilis 4 5 |implicita| 4 5 | ilicis 2 peerOTawil net 
6 | rugosa 3 6 | drakii 5 6 | futilis 3 

7 |implicita| 7 7 |implicita| 4 

8 | futilis 1 8 | rugosa 5 

9 |rugosa | 4 





General Chronological List, Northern Illinois 
1, anxzia; 2, fusca; 3, inversa; 4, tristis; 5, drakii; 6, implicita; 7, ilicis; 
8, futilis; 9, rugosa. 





242 BULLETIN No. 186 
SUCCESSION OF SPECIES IN CENTRAL ILLINOIS 
1907 1908 1909 1910 
(Om ‘|On D » D mn 
zs ‘Esles ESle 8 #sle8 ES 
S| ectes |2E|2H| species [Hl 2 Z| Species |Z ELE 2! species 1H 
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1 | fusca 3 1 |fusca i 1 |hirticula | 2 1 | fusca 2 
2 | inversa u 2 |tristis 6 2 |implicita; 1 2 |inversa | 3 
3 |hirticula| 5 3 {inversa 4 3 | fusca 4 3 | implicita} 4 
4 |implicita|; 2 4 |hirticula 2 4 | drakii 5 4 |hirticula| 1 
5 | futilis 4. 5 |futilis 5 5 | ilicis ri 5 | tristis 5 
6 |jimplicita | 3 6 | inversa 3 6 | futilis 6 
7 |rugosa 7 7 | futilis 6 7 |fraterna | 8 
8 jcrenulata| 9 8 | ilicis 7 
9 horni 10 
10 jilicis 11 
11 |crassis- | | 
sima 8 | 
General Chronological List, Central Illinois 
1, fusca; 2, inversa; 3, hirticula; 4, tristis; 5, implicita; 6, futilis; 7, 
rugosa. 
SUCCESSION OF SPECIES IN SOUTHERN ILLINOIS 
1908 1909 1910 
5 eo | (oo oe 
bm 22 | pm 2a] pe ag 
Ps AS | eS EST HS A. 
ga og | 88 | 38 23 | 88 as 
a Species AD AL | beats Species weoleas Species ae 
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5 BY Bo | 8S 5, | Si oo 
38 oA lOS oA] OG ro A 
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1 |micans 2 1 |fervida Ag, | | 1 |vehemens | 3 
2 |hirticula 1 2 |vehemens 15 2 |tristis 9 
3 | futilis 3 3 /hirticula 5 3 |fervida 8 
4 |vehemens 8 4 |rugosa 16 4 /|fraterna 5 
5 |fervida 4 5 |micans 4 5 |futilis 12 
6 | bipartita 12 6 |fraterna 6 6 /micans 1 
7 |fraterna 14 7 |corrosa Poly 7 |hirticula 2 
8 |implicita 7 8 |bipartita 3 8 |profunda 4 
9 /|profunda 9 9 /profunda “ 9 /corrosa 10 
10 |congrua 11 10 |futilis 9 10 |bipartita 6 
11 |crenulata 6 11 |praetermissa | 14 11 jcrenulata 11 
12 |corrosa 5 12 |implicita 2 12 |implicita 13 
13 | delata 13 13 |crenulata 8 13 | forbesi 7 
14 /|anxia 10 14 /forsteri 13 
15 |forbesi 1 
16: jeongrus,. -| D2 oe 
General Chronological List, Southern Illinois 
1, vehemens; 2, tristis; 3, fervida; 4, futilis; 5, fraterna; 6, micans; 
7, hirticula; 8, bipartita; 9, profunda; 10, corrosa; 11, crenulata; 12, delata; 


13, implicita; 
































[ February, 









































14, congrua; 








15, forsteri; 


16, forbesi. 


243 


MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 


1916] 




































































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Species | 
lig | 19|20| 21| 22 |23|24/25|26|27|28| 29 
Futilis. . 11; 4| 259; 246) 7110 2/381 
Anxia... 2} 3 3 1| 
Fusca..; 8| 8 8 3 1 
Rugosa. | 34 95/| 89 82} 141} 3;16| 8 | 1 4 
Inversa. 1 1 
Implicita 2 
Drakii. . 1s 
Nitida... 
Tlicis. \s 
Micans.. 
Tristis.. 
Congrua, 
Prunina, 2 
Fraterna 
Balia... 
Forsteri. 
Crenulati 2 1 
Totals.|34/ 118/99| 305] 392/11/27/ 4|8 |85!1718 
Totals 
16 |19 | 20 |22 | 23 |24 | 25/26/29 | 30 
2 14% 1 itt 69 
50 
L7 2/1 144 
3] 2 4il 
17/12/16] 8 12) 3 430 
4| 2\ 6 7 126 
1 1 54 
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p's 7 
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1 
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| 








OO Totals 
5116 |19/| 20 | 21 | 22 | 29 | 80 
(1) 15| 4 111 -4:)-4h0> 2 658 
7| 2116] 11! 38 1 | 29 389 
i8} 41] 6 36 1/141 1045 
2| 9 8 137 
7| 13 5| 4 2 54 
‘8! 9 46 
2| 5 8 22 
1: 3 7 18 
1 
4| 81 201 256 
73 2 19 3 228 
ah. ¥ 3 8 
'2|129| 26 | 74 |819| 8 |22 | 49] 2857 




















Totals 








Al 1628 
172 
1960 
1054 
229 





————— ee eee 


Species 





Anxia...| 4 
Fusea<.<:}=1 
Rugosa..; 1 
Inversa.. 
Implicita. 
DTA KI... 
Nitida... 
dlicig. =... 
Micans.. 
Tristis... 
Congrua. 
Prunina. 
Fraterna. 
Bais, 
Forsteri. . 
Crenulata 


3 
1 


Totals.|22/7 | 198] 39 


Dares oF CoLLECTION, NoRTHERN ILLINOIS, 1908 











20 | 21 | 
Futilis... “f| 3 


145 





























































































































RTD ie he TSE EIEN NT I oe a ER ey aot A 









































































































































244 








May | June | _ July ee Totals 
24|_25| 26| 27| 28/29] solsil1|2| 3/4] 6| 6] 71 8 |_9 jar] 12| 13/14/16]17/18| 19|20| 21| 22 |23/ 24/25 |26/27|28| 20] 11 71 27 628 
die oy 46 13 | 82) 7 104 80) 64115) 274) 201 488 43 7) 1 4 2 7 11] 4| 259) 246) 7)10 2 | 31 1 eS 
1 14 1] 5 8 2} 6 | 87> “29 3| 13 2| 4 7 5| 1 1/13 2| 3 3 1 og |1060 
78| 329! 50| 377) 253/32} 185| 21 7] 71\ 69 7; 69 4} 724% 791-9 6 5| 3 8 8| 3 8 3 1 10b4 
ae 2,| 3 2 Li St 0S a 243| 197 10/14/34] 95/89| 32) 141] 3/16/38 |1] 4 g {10/2 054 
60; 85; 20] 60) 22] 4 2 1 6 6 1 9 1 1 275 
3} 6} 2) 199) 6) 2) 8 Lin 24) a4) 28 | 2 ee én 
3}. 2}-°18} 10] a1} 2 11 A 24) 6] S25 1/38 75 
2| 19 1 23 1 29 18 
3 3 1 6 3 1 1 19 
8 8 5 1 2 0 
2 4, 4 
14 14 
2 3 2 7 
1 1 
: 2 
| 5 4 9 
8 1 2 1 ee ee i! 
876) 111) 723) 290/85 | 217/10] 27 | 125) 187/231 816| 173) 552] 165| 185! 7 | 261/_207| 6 [111491841 118/90 | s05|89a\11 |a7 4 |e |a5l7 \e li |a laa | 6569 
DaTES OF COLLECTION, NORTHERN ILLINOIS, 1909 
Species BAY | — June Totals 
11/13 |14/16 |17|18 | 21 | 22 |23 |24|26|27 | 28 | 29! 30 11/3 |41/5|6 | 9 |11 |12|/13/15]16/19 | 20/22 | 23 | 24 25 |26 | 29 | 30 
Anxia....| 1 5) 4 2 | 8/11 3 3| 4) 8) 12) 2 6) 8B 152 Tit ee 69 
Fusca.... sd ey So Ge SS 1 ls ety 3 1 5) 6| 4 Se et] 50 
Inversa. .. 2 2 6-4} 211111 5} 1| 2| 10] 2] 6 9| 53| 8 | £7 eS | 144 
Tristis.... 1 | 2 |60/11|15/|14 |27 | 46 6| 61] 21] 49) 55| 30 3424 1/ 3/2 All 
Tlicis..... Bi 8-129-1 98 44 | 42] 85) 32] 63] 10 16 | 63/29] 2 |17/12/16| 8 12 3 430 
Drakii... 3:| te \s61 7 8 10] 36] 9| 16] 5| 4 4| 1 4/ 2) 6 7 126 
Implicita. 1 51-2 10-1 5| 14 156424 1 1 54 
Futilis.... | 1 3/ 1); 6] 6) 2) 8} 35 3 | 30] 85) 5) 2/10] 5| 8/11] 4] 1 [268/11 | 97 | 82 637 
Crenulata. 1 3) 2 1 7 
Rugosa... 1 36 6; 2 7 47| 1 |380| 12) 2 144 
Fervida. . 1 1 
Totals...) 1 | 7 |12| 9 | 8 |60|14'24 | 28/48 |93| 1 |72| 9|189]108/104|201\102| 10 | 3 | 89 1168] 45 6 [57 | 24/29/74] 5 | 32 801/13 | 97 85 | 2073 
DATES OF COLLECTION, NORTHERN ILLINOIS, 1910 
Soaaeee April | May June Totals 
14|15/28|29 | 6 |15| 16|18| 19]25| 27 1|5 1718 | 9 |10 |11 |12]18 | 14 | 15/16 | 19 | 20 21 | 22 |29 | 380 
Fusca.....88 |29|}56,/44) 2/33) 97/86] 40 74) +11; 64; 1} 7) 8 11(--5) 1ip 15) <4 LT 42) dt 653 
Futilis....| 1 | 1 1) 8|88/17/|25)| 2 |22 |23| 83| 79) 7} 2116] 11 38 1 | 29 889 
Anxis.... 90 1/175 139 |20/ 125 95) 51] 2| 4/81 7 | 30| 69| 58| 41] 6 36 1/14] 1045 
Inversa... 2 69 27. 19 1 2| 9 8 137 
Drakii-... 7 4 6 6| 7| 18 5| 4 2 54 
LEvistisices. ct 9 5 5 18; 9 AG 
Hirticula.. 6 1 2%. 35 8 22 
Tlicis..... | 4 8 1] 3 7 18 
Balia.....| 1 “ a 1 
Implicita. . 1 14 201 256 
Rugosa... | 1 129} 1 73) 9 19] 3 228 
Crenulata. | 3 ee be 2 Bink 3 8 
Totals. . | 89 |121' 56/441 2 | 34| 368/86] 179/20! 237| 107|161| 41\28 |115| 2 | 22 | 30 256 160|122|129/ 26 | 74 [319 | 8 | 22 | 49 | 2857 


245 




















































































































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|14;16 | 17|19|20| 21 | 22 23 |24| 25| 28| 29 
Mh ae 18h Sar 1S; “Lp 8 1s"° } <9 1 2 
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31 4 1 1 
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9| 661188| 1018'499|610 201|437| 35'642| 4' 15| 8| 65| 13| 4! 33 
Totals 
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; 2 1] 706 
36 87 2 |22]| 4495 
| 133 
87 
1 25 
4| j 6 
135 
| 2 
1 11 
2 37 
10/41 | 5 |23{ 5637 
WISE SST | July Totals 
11 |22 |23 |24 |25 |26 |27\28 | 30] 1 | 2 | 8 | 11 |20 \o2 
84/1 | 8| 5| 5| 9 3, 11 38 1 1248 
2 | Hoa at: 1k a 944 
24171 6 5| 15 1 4 633 
31| |237|19 |349/247|133| 92 | 119] 77 |141/ 40 |17 1} 7805 
3 
10 
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2 1 ai 1 1c 2 315 
5 3 5 1 2 3 52 
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Totals 


2517 
689 
1207 
22811 
42 
1047 
1695 
272 


246. 


DATES OF COLLECTION, CENTRAL ILLINOIS, 1908 < 
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: wate May fe June ae 2S ee 
7 Species | a a a a Te a RS a cs pe ERE a MN SE Te a en EE CS a ee, ee ea ee ee ee Pi ta ee | 7 | 10 13| 16] No | Totals 
| 20| 21, 22) 23) 25 9| 10| 11| 12) 13) 14) 15| 16| 17| 18| 19 | 20 | 21) 22 | 23 24| 25| 26|27\28|29|80| 31] 1 | 2 $2 4.| 5) 6 | 7 | 8 |-9 | 10 11|12|14|16| 17|19 20 | 21|22| 23 |24| 25| 28| 20] 2| 4 | a 
z a i Bre | { i} | : G ae 
= Fuses; ..:- 82| 14) 64) 87) 88; 29,116, 23 29/34/55) 27| 40| 58| 887) 71) 6)113) 49; 39) 169; 26; 42; 38) 9) 5 21; 14,. 50| 428) 5| 6| 5; 68, 56) 9| 67| 49| 1) 13; 384, 12; 4) 8; 13; | 9 1 2 zee 
= SEs eas ae = : 4 se tor An 5 | 38 3| 69 1 4 6) 10 2 1 3 3 | 2 6 g| 15| 12! 5 2| 8 2 1207 
Versa... 3 58| 20 97| 4] 8/285| 16) 44| 124; 19] 8 3| 10 10|.11| °51| ~ 106| 12 41° 61) 12 
Hirticula. . 1 2/291 257| 23/156 1022 46| 10/443) 42 425| 573| 976|187| 38| 24/186) 26] 31\572) 634! 10786,364| 98| 54/1128 46 1801 26 58/142 680 323 591 159 359 30'559| 4| 15) 8} 62) 18 33) 9 33 22811 
pape: 3 3 6 6 
Futilis..... 6| 4| 36 82| 85) 2| 8| 27; 17| 112| 46| 11 3 4| 35) 2638 47 5st 4 51| 16 13| 67/109| 8) 20; 8| 5| 1 5 tae 
Implicita. .. 9; 2| 70 48| 3] 12| 23} 2| 12] 73| 43) 10 1 198| 13; 5 14/268; 1) 1| 320|146|. 6| 13) 33 12| 213} 10} 4| 12] 48 70 : ee : 
Rugosa..... 2 21} 10; 14 8| 8 1| 37 57 1 38 pie 1) Ft 31 4 1 27 
Crenulata... b ee 10 5 10 21 1 | p Bes 58 
Horni..:..22. 5 3 2 10 4 38 1 2 64 
Hicis = +. 4 2 1 7 6| 6 1 1 4 + 2 i 1-2 2 2 1 1 7) 52 
Crassissima. Ps a3 27| 65 : es eke 
Totals... | 82) 14| 64! 87| 88] 58/157! 24| 4| 96.825 |431 115/364! 68|1702|159| 49 946 |138/543| 1119| 1122|356| 41| 41/202| 261 267 686 1005| 114531733 /107| 62 1639/251| 15|14191109| 661188] 1018'499|610|201|437| 35'642| 4' 15] 8| 65| 18] 4! 83/ 10| 1| 80| 80546 
_4! 96 825/431 115/364’ 68/1702|159) 49 946|188 543|1119| 1122/356| 41| 41/202) 26] 267 686 1005! 1 5 '2011487| 851642| 4! 15| 











DATES OF COLLECTION, CENTRAL ILLINOIS, 1909 










































































































































































































































































= ae May June | 
Species |——— ——- - - Totals 
29} 5 | 8 |12/15| 17|18|20/21| 23\/27| 28\s0| 3111 | 3/415 16 | 7 [10/11/13 | 21 | 22 | 23 | 28 29 | 30 
Hirticula..| 1 18) 5| St) 9/2 | 5) 158 2) 119, 2) 57) 70) | 67 73) 5) 85) 1) 1) 9 Giese Sea 1} 706 
Implicita..) 8 1| 34/11 | 8/21] 345 79| 596) 2 | 181 |390|/675172 405,104! 59 257/366 285| 3 [151/336 37/2 |22| 4495 
Fusca.... 23 59) 9 9/ 2/1] 2} 14) 2 6| 2 1 1 2 | 133 
Drakii.... 3 8} 2} 15 Sieetb ss) ered 7} 2-8} <9] 1 87 
Tlicis..... 1 6 2 2] 4 1| 4 2 2 1 25 
Anxia.... i | | 4; 1 6 
Inversa... 83| 9 9) 8} 2 18 1| 3 2 4) 1 135 
Horni.... 1 | 1 2 
Rugosa... 1 4 4 1 1 11 
Futilis.... 1 8 3/23 2 37 
Totals..| 9 | 23 | 4 |156|/24| 103/25 | 8 128] 5501851 739] 9 | 19714811678 [248 500/113 11052721374 310 26 |1611340|41 | 5 |23| 5637 
DATES OF COLLECTION, CENTRAL ILLINOIS, 1910 
ESET = SS Se eae TT ET RSE SEE A SE 
, April May June July 
Species ee l = Seen oe Totals 
9 |10|18 | 14 |27 (28 |20|30 | 6 | 9 |10|16/18/19 |20| 21 |23|25\26| 27 }1]21/4/5/|6 | 7 | 9 |10]11|12 [13 /14|15 1/16 | 17] 18 | 19 [20 121 22 128 24\25|26 |27\|28 | 30] 1 | 2 | 3 Sere 
Fusca..... 32/73 | 4 |51| 2 (86 187|11 | 8 | 64/12) 56, 5) 4| 24) 71/15 23; 85 | 23|/ 1 | 27; 10) 2) 92) 9) 1 | 78| 70] 5 | 27\/15| 22) 4] 11! 9:14) 84)/1 1) 8] 5) BL 9 See ae 1 ef ie 4946 
Inversa... 2 3/31} 7] 1 |112| 8| 20| 9| 38| 20) 48 59 80| 218} 38] 1| 146] 81 DoeTD 26, 2) 10; 2) 1) 3/11| 2 rE tae ee aes Be | 944 
Implicita. - 1 1 Liss fe 1) 11/22| 1 | 74| 85 | 29 4) 10/13 | 90/ 28 1 | 58) 23/49 | 21/94 | 14/17| 13| 11115! e417) 6 Bi 15| a1 4 633 
Hirticula. . 1 | 81 4| 4/156 5| 9 /139) 1385) 6 40) 11 | 56) 2 (292) 87/16) 938)119| 858/585) 23 |400/ 42 [570/18 |188205 362/331| [237/19 |349/247|183| 92 | 119] 77 |141/ 40 |17 1 | 7805 
Baliac.. ss | | | 
a | | 3 
Drakii.... 1 1 1 6 1 | 
Tristis. ... 2 4 1 2| 167 5) 2) 58 84) 7 3 2) 71 9| 8 3 2 1] 1 i aoe 
Futilis.... 9 1} 1| 8 5| 20) 4 1) 1] 2 37| 4 133| 36 2| 4/ 2 | 20 1| 12 2) 4): 2 1 a4 1 1 1 2 315 
Fraterna. . 1 3 6 1 | 8 3; 1 2 re ee | 4| 5 3 5 1 3 3 52 
Anxia. ... 8 1 1 2 care a 9 
ehemens. | 
Hlicis..... 5 1 ee wee _ 4/2 4) 2 2 8 2) 1} 5) 4) | 2 5| 6| 1 Ad lee le 
Rugosa... 1 | 1 1 1 1 es 
Fervida... | 1 
Villifrons. | | 1 
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Totals.. | 32/75 | 4 | 51/3 |91 1214/18 | 4 1187/27 240 20 | 17 |199/1715|47 | 1 |199| 82 1191] 6 [580/120] 34 | 1465276) 2 [5591654 79 503/83 |630| 55 |218/238 424\461 8 261/26 [373 |2931139|97 | 126| 85 |i48|42 la7 | a 141 11435 
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Pervida 
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Totalig— 


Speci SUPMRoTICMCTETETIET _ August — 
24|25|26|27/28|30] 1 | 2 |12|15|24|26|27/|28\29] 5 | 6 |26 
2 3 | 
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June 
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248 











| Totals 


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Totals 








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270 
422 
1011 
124 
1 
1479 
1831 
2 1025 
210 
34 
844 


| 1267 


5 
589 





248 


DATES OF COLLECTION, SOUTHERN ILLINOIS, 1909 





5S ge Sena eo a nr ee RS ON IE ge a ene 












































































































































Species OVE VEE EE TEE TIETEETaRS EE TIT CHEETITRETIETA June SOU ee es ae | et Totals | 
—__|_174 18/14 |17\18 |19 [20 |21| 22\/24\25| 26le7|2s|29} 2/3 1517/1819 |10 11 |15 | 16 |17 18 | 19 | 20 | 21 | 22 | 23 [24 | 25 | 26/27/28] 30] 1 | 2 | 12/15 | 24 | 26 | 27/28/2901 5 | 6 126t __ hm | 5 | 6 | 26 
=a RSs lise CS ee ea 2 14) 1 2| 3 3 | 6 1| 14 2 3 are eae eae ee ea ee 
Vehemens.... 7 6 2 1 5 4 8 3 1 
Hirticula... 51| 46 1 2| 20| 13) 380 44| 3 1 4 5|16| 8 2 591 
Rugosa..... 8 5 15 2 30 
Micans....- 16| 31 1; 8| 4,10] 22| 31] 20° 385 10; 2} 1/18] 6} 16) 2 2 ze 9 |106 2 185)| 4 2 18| 1 759 
Fraterna... | 17| 5 5| 14: 67| 27 71| 5 38 ; 20| 2 44 5 | 12 1 | 25 12 7 377 
Corrosa....| 18) 5 Pe ee gk 19 117 
Bipartita. .. 3; 5| 8154 |109| 92 298; 2/| 52/109) 2 52 25 793 
Profunda. ..| T| 5 pa 1 | 17/25) 4 53 33 3 20 1 219 
Fusca...... 1 | it 
Tristis..... 1 13, 11 | 2 27 
Huts, ..s:: 2 7| 5| 4| 37!) 44! 23) | | 18 3 4 1 | 148 
Praetermissa 1 | T1745 44 \ te 1 1 46 
Anxia....-. | 1 | 2 1 4 
Implicita. .. 1| 79 |865/| 20/410; 28 4l172| 5/1 2 8) 59 |112 154 10 (868) 5 st 17] 1 1821 
Alicis==..= << 3 | 2) 16 4 : 22 
Crenulata. .. 6} 2| 58 2) 24) 1 2} 7] s\2 1] 6|33| 3 7 4}10|11/ 9 | 8 ae 
Forsteri.... 2| 36 1 8 47 
Delata..... 9 12 1 15 
Forbesi..... | 2 . 208 4/1 8 | 25 14 | 68 |247/411/541 550] 331/361 2766 
Crassissima. 3 6 1 10 
Congrua.... 5 | 14| 8 | 46 2 70 
Calceata.... 1 1 
Longitarsa . es | | 15 | Be, Cael 

Totals....| 9 1146/121\14 | 58/121 113| 93 4261146 551| 1044/53 |16| 2 1185/231/316| 65 | 75 |1891124| 84 |131! 4 |412170 | 16 | 28 1560' 16/3718 144177! 4 120127] 49 |35 | 15 |14 | 63 '249/411 541|550|381'364| 2 8209 





























DATES OF COLLECTION, SOUTHERN ILLINOIS, 1910 


a a 














































































































: March | April May | June July 
Species | — Totals. 
27 \28 |29 |30/31 J1 | 4171819 |18 {15/2912 | 3 | 9 |10116|17/|18| 19/23 | 24|26|27|30]12 | 9 | 11|13|14 |16|17| 30 }21 | 25 

Vehemens...| 38 | 56 1134/378,73 [66 121| 3 |135(|163 72 4) 23 1 1267 
Tristis..... | 2| 2 2 4; 6 3 8; 9 117; 68| 1 | 17) 81 | 270 
Fervida.... 2/12| §6| 8116] 3 | 18) 78) 2| 21| 27 17| 4 | 20) 48| 3 MS Oi Atel ooo Ad) cee [ares ine 6 8] 5 422 
Fraterna....| 2 | 2 4; 10 10; 1)100| 6 15| 98 174/107; 42; 22)108) 22! 85 23) 74| 90 10| 2| 4 1011 
Futilis..... | 2| 4 10 2| 20 6 Git 1 14 Sted 124 
FUSCS coc. 1 1 
Micans..... 4 21165| 4| 14 112] 24 181/270] 11 |142| 42| 28| 50/174) 17] 88] 17| 8) 87|110 20|/ 4| 5 1479 
Wicheniac 4 2| 88| 6|17| 1] 65/12 | 72 |253 225| 51 |263| 42) 53) 96380] 11] 30] 10) 14| 23/ 52 1| 60 1831 
Dectanda cf. 7 187) 25 94,242| 4| 74) 15) 63] 14248] 15 23| 6 2\ 4 2 1025 
Corrosa.... T 2 2 81 24 68) 26 210 
Delata..... 2 2| 2 21 4} 1 2 34 
Bipartita. .. 14/571] 8 26| 8 2 7 135| 26) 1 | 46 844 
Drakii..... 4 3 7 
Tlicis......- 2) 8 4 6 oh.2 2 1 22 
Crenulata... 7) 1) 2) 2| 8| 10) 11 7] 1| 8| 24) 63 24 6] 1 169 
Forsteri... 2 li 
Prunina... 1 
Implicita... 44 4 9| 16] 1 74 
Orassissima. 56 56 
Forbesi..... | ead ei en eas SP et ie ee Naan ne et ee ete a feces me ee ee, RB eens eee cee aig 270 589 

Totals... | 38 !62 1150'888'73 169 160! 6 |167'544!12 '152'581 1498! 71 | 72 ‘609 917! 98 (779.374 '194!201 195711511246 11451102 246 |3411207/108| 79 63 3222701 9447 











1916 | MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 249 


VARYING ABUNDANCE OF THE SPECIES IN DIFFERENT YEARS 


An examination of my data of the relative numbers of specimens 
of the several species in successive years gives little reason to suppose 
that periods of unusual abundance in any locality are commonly sep- 
arated from one another by an interval equal to that between succes- 
sive generations of a species. Times of abundance and scarcity are 
much too irregular, and either one or the other is often too long con- 
tinued, to make this a plausible explanation of the facts. In view of 
the number and effectiveness of the animal and vegetable parasites of 
white-grubs and of the insect parasites of the beetles, it seems much 
more likely that parasitism, possibly more or less modified by the 
weather of the period, is a principal cause of these frequently enor- 
mous fluctuations in numbers; and even if a periodicity appears 
corresponding to the length of the life cycle of an abundant species, 
it is likely soon to be broken up or set aside by a consequent rapid 
multipleation of parasitic insects and annelids and the spread of 
contagious diseases due to parasitic fungi and Protozoa. The practical 
importance of this conclusion is evident. In the absence of such para- 
sitic disturbances of the normal course of events, a season of injurious 
abundance would be always followed by another such season after a 
period of years sufficient to bring the next generation of the abundant 
species to the same stage of larval activity; and if the species con- 
cerned and their life history for the latitude were generally and ac- 
curately known, measures of precaution might be taken, especially 
with crop rotations, of a kind to reduce to a minimum the injuries to 
be expected. This is indeed the case in Europe, with the Old World 
representatives of our American white-grubs—the vers blancs of the 
French and the engerling of the Germans. There the so-called ‘‘ flight 
vear’’ of the beetles or a season of serious injuries by the grubs, may 
bs aeeurately foretold for any locality and measures taken accord- 
ingly; but in Europe no parasites of these insects are known, and in 
their absence there is comparatively little to interfere with the peri- 
odical recurrence of these seasons of their destructive abundance, es- 
pecially as the species are but two as compared with the thirty-four 
species in Illinois alone. To understand the probabilities with respect 
to our American white-grubs it is, in my judgment, at least as im- 
portant to know the status, at the time, of their most effective parasites 
as to know the life histories of the May-beetles for all our latitudes 
and climates. This is especially true because of a latent possibility 
that the grub and beetle parasites, especially the fungi of disease, may 
be so cultivated and distributed as to assist materially in the control 
of the insects—an undertaking in which there have been many failures, 
but one the possibilities of which have been by no means exhausted. 
We have lately found, for example, that a new annelid parasite of 
the grubs is the cause of epidemic destruction of them, and that it 


250 


BULLETIN No. 186 


[ February, 


may be readily bred and grown in great abundance and by the simplest 
methods, on raw egg. 


RELATIVE ATTRACTIVENESS OF DIFFERENT KINDS 


oF TREES AND SHRUBS TO MAY-BEETLES 


The following is a list of the plants from which our Illinois May- 
beetles were collected from 1907 to 1913, with the number of collec- 
tions from each kind of plant, the number of specimens which these 
collections contained, and the average number of specimens per col- 


lection. 


PLANTS FROM WHICH MAY-BEETLES WERE COLLECTED 











Food-plants 


No. of specimens 





1 pile ka ale SS) 


Box-Older ic 1s. 
Blackberry... 4 sau 
Cataipa i sicy fas 
Cherry iain nc 


CCT aE Meee hea ay 
Currant, flowering. 


Grane... sau 
Hackberry... o..2 -/: 
Ta Wiuorn ina. = wi 
EDR ONY, Saris Soak 
Honey-locust...... 
Honeysuckle...... 
Hornbeam >.) ov% 
Horse-chestnut.... 











s| No. of collections 


bo 


bo 


LO 
~IOT RB DONDE Ee Re oO DO 


bo po 





| No. per collection | 














iv] 
[=| 
o 
£ 
oO 
Food-plants Ss 
q4y 
° 
3 
s 
Manian. edie | 308 
Mountain ash..... 760 
Negundo..” 6.0 16 
Oak ds: Soe eek 18,162 
Osage orange..... 1 
Peachy st exteems 434 
Persian olive...... 15 
Persimmon. :\./a06 1,849 
Plums. casas 171 
POOR UAV Yelena oe 22 
Paoplatinceets se t? et og 
Red bite aetna. se 14 
TOS Rey ot aie 476 
POO Wisin came 9 
Syeamaresiess. Wie. i33 
Surry gra) aivege 6 
Tree of heaven.... 14 
MTree ere a 47 
Walnitit. sts.) i 1,691 
Wilkow §. erste "stages 8,733 
Food-plants..... 73,656 
Miscellaneous... 3,362 
La hte eee fame 35,498 
Plow-furrow.... 1,937 
Data deficient... 40 
Votalenesaia 114,593 | 








No. of collections 


bo 
CO pa — 
mM Oblmiowe 
OH No. 
RH OR we 


bo 
iaR SC) 





per collection | 


In cases where a sufficient number of collections were made to 
give us a fair idea of the attractiveness of the plant to May-beetles 
at night, we have the means of a significant comparison of these trees 
and shrubs as a lure to these insects and a consequent source of danger 


to the crops of neighboring fields. 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 251 


If we adopt twenty collections as our minimum number from any 
kind of tree we may make a list of our common forest, shade, and 
ornamental trees in the order of their attractiveness to May-beetles. 
In the following, the number after each name is the average number 
of beetles per collection taken by us from that tree: oak, 79; per- 
simmon, 77; poplar, 73; hickory, 42; willow, 40; walnut, 34; linden, 
19; maple, 19; elm, 18; hawthorn, 16; ash, 12; hickory, 10; box- 
elder, 5; honey-locust, 4. Making due allowance for the unequal 
character of the collections unit necessarily used in the computation 
of my averages, I think there can be no reasonable question of the 
eeneral meaning of the facts represented by this list, and that we may 
rely upon these index numbers sufficiently to divide the trees of this 
list into about five groups, as follows: (a) oak, poplar, persimmon ; 
(b) hickory, willow, and possibly walnut; (c) elm, linden, maple, and 
birch; (d) ash, hackberry, and hawthorn; and (e) honey-locust and 
box-elder. Perhaps the only things to regret in this list are the ap- 
parent marked preference of May-beetles for the oaks and the indif- 
ference of these insects to the box-elder. While our field notes do not 
make sufficient mention of the various species of oaks to enable me to 
recognize differences among them as food for May-beetles, some of the 
most experienced and observant of my collectors tell me that the 
shingle-oak (Quercus imbricaria) and the oaks with rounded lobes to 
the leaves, like the white and bur oaks, are much more resorted to by 
the beetles than are the red, black, and pin oaks, and other species 
the lobes of whose leaves are pointed or bristle-tipped. The most 
dangerous tree on our list is the poplar or cottonwood, of which the 
much used Carolina poplar is simply a variety. Certainly in the 
linden, maple, elm, hawthorn, ash, hackberry, and honey-locust, to 
which we may probably add the red oak and the pin-oak, we have a 
sufficient variety of fairly safe trees from which to choose for planting 
either on the village lawn, the country roadside, or the rural home 
premises. 


252 


PRINCIPAL FOODS OF THE PRINCIPAL SPECIES OF MAY-BEETLES 


(Ratios of the ntmber of specimens of each species from each food-plant to the whole number 


of specimens of each species from all its food-plants) 





BULLETIN No. 186 


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Implicita. 
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Inversa Tristis Rugosa 





lar illow| Oak Elm | Poplar | Willow| Oak Elm |} Poplar | Willow| Oak Elm 


ee es ee | ey | ee a a | ae, pe 
























































gi/2igi/Zigigigildidlsiagisidi Si dlaigisgisgigidisig 
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253 


SPECIAL COLLECTION FROM FOUR FOoD-PLANTS, URBANA, ILL., 1906 











































































































































































































































































































ee a a re IE SP I ST a ae a a RNR a a PR A A aL pe eRe ye SS Ig I Gee aa a he TT . J 
Fusca Implicita Llicis Futilis Hirticula Inversa i eee ee ee 
Date Poplar | Willow | Oak Elm | Poplar | Willow| Oak Elm | Poplar | Willow! Oak Elm | Poplar | Willow! Oak Elm {| Poplar | Willow| Oak Elm | Poplar | Willow] Oak Elm | Poplar | Willow| Oak Elm | Poplar | Willow/ Oak _ Ein 
Mata to Lt oe eile | er eh le oe eee ee Sig he tet cea | o hal oe Pa tela | © fa | eet of a4 ols | ol ee Po ee el 2 od | oa te 4 oe Ge + oe 
SIZIS EISiElSlEls £leleie 22 8lsi2igielg fgielaiglg/e elejelelelg/gig/2lgizlelelgiaial2/e)2isl2iejzlelg 3 3 Sio!|Sio/S8|o 
3 S Ss s fon] os) 3 is) t 3 3s 3 3 3s 3 oS S ®o >) Oo @ 
BIB IRIS ISIRIAIR ISIE RIES PIAS IAB IRIE IS SIS EI SIS ISIS IS ISISISISISISIS SIS ISIEIS SISISISISIS ISIS SIS lel Sle lS leleielaleisiela le 
May 14 1 2 48 | 251 46; 31; 39,3 | 1 4 
15 So lg pe be oe | 44! 53) 28| 37) Pe ae | 
16 46°31 21! 85) 6| 17 | 
17 1 | 61/103) 88| 71; 4 | 9| 6/17 Bee 
21 | 18; 14). 8} -4| ; é 5 3 : : ; 
22 | 15| 14} 3] 6| ‘ 3 
23 | 110,124: 72) 97, 4/11) 14 2 1 1 2 5 | 2 4/2)|2 Tis Biet 1 2| 1 
24 | 16/14) 8] 9| eiciea Bisel 2 2 2 
25 | 28) 21| 13] 14] | | 
26 5| 4| | | 61) 79| 42) 50 ris 13) 9 4/1 1 91-71 1; 1 
30 = 4) iy 6 | 6; 5 : 1 
31 31)-56) 15|.24' 1 | 5+-3 23 , 27| 24° 1 Cry Sr et a oe Pes ay 3 te es eR 86'17| 6| 8 2 6! 5 
June 1 box 16; 72| 4| 39! 4/14 4 3 | 1 11} 6 | 3; 1 
2 | 24) 63| 16| 42) 5 | 24 8) 8 12} 4 | 
4 S67 ate aap 1.23 |g 19| 14 S21 ee,| 1 5| 16 3/1 
5 | 6) 41 13 | | 24| 24 12} 20 | | pee) 1 
6 ese 4) 33 en ae ee ! 12; 3 14) 1 See 6| 3 l 3| 8 
7 | 1/6} | 3 1/2 OL Bh 1 20 | 16 7| 7 | | 4| 17 
9 | 3} 11; 1) 24 Si 11-8 1 | 15} 6 * 1 5| 4 14 | 16 
15 | | | B21} 41-6 | | 17/ 26) 4 | 13 | 8| 9 3 | 7| 8 5 
16 | 7 10 | Sees 4) 1 | 1} 1/1 11 | 14 2/3 
18 | | e581 47) 6 | 16 1 pals 2121 D8 Sit 11 | 30 2/7 
21 sa | 15 1 1 4/16 3| 6 
22 | | | 3 | 1 | | V4 2 
28 | | | 1 1 | 
Totals. 24/15/4/21/11 _ | 485|971/301|554| 8 |27/40113112 | | [4 |187|i80/ 7 | 14453 1/20| 7 15) 81-4) 16.47) 6 14| 8511017 fe 8) ae db) ee 56 (11a|. | + 4 lela: 


1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 255 


PRINCIPAL MAY-BEETLE SPECIES ON PRINCIPAL FCOD-PLANTS 








Principal oak species: Principal fruit species: 
tristis, 93.7 Jo ppapple; 16. % 
profunda, 52, | cherry, Alas 
hirticula, 43.6 ’’ aes peach 24.2 7? 
ilicis, " 42.2” forbest 4 Fium, 8”? 
fraterna, 42.2 ”’ eee 
fervida, 41.4 ”’ SS 
micans, 34.2 ”’ 
“eae apple, 9.3 % 
Prineipal hickory species: eenaelte aii re 
profunda, 38. % futilis 4 es erry, iH os 
fraterna, 35. 7? Ns abd) ra 
hirticula, 18.8 ’’ 
fervida, japan £: ( sigue = 
Prine} re AGS apple 19.6 % 
rincipal eo), species : blackberry, 22. ”? 
micans, 980.7 % imversa others 16” 
fervida, 31.4 ”’ ; ; 
Praserna, «18, 77? 43.2”? 
Principal willow species: ( apple, 32.5 % 
bipartita, 86. % implicita, others, iP ee 
rugosa, 32.4 ”’ 4 
implicita, 27.6 ’’ * 33.7 7? 
anxia, pA 
1G5e?? blackberry, 9.2 % 
HOG | cherry, Pa soa 
" ay oP 
Principal poplar species: hirticula ° preg? 7 Me 
rugosa, 38.8 % seareakt : 
implicita, 32.5 ”’ 
fusca, Let \ 148! 
anxia, 10 5a27 apple, 7.1 % 
blackberry, 4.7 ”’ 
Principal elm species: fusca gooseberry, 3.7 ”’ 
anxia, 33. % others, bE 
ilicis, Divo s poe 
inversa, 14.2 ”’ L 17.3”? 


PRINCIPAL KINDS OF FOCOD-PLANTS OF MAY-BEETLES 
BY SECTIONS OF THE STATE 


Northern Species 


Fusca: poplar, willow, oak, hickory, ash, elm, apple, walnut, and others. 
Nitida: hazel. 
Anxia: willow, poplar, apple, oak, and linden. 


Northern and Central Species 
Inversa: apple, elm, blackberry, and ash. 
Rugosa: poplar and willow. 
Drakii: willow, poplar, oak, elm, hazel, and blackberry. 


Central and Southern Species 


Hirticula: oak, hickory, blackberry, and others. 
Fervida: oak, hickory, persimmon, and willow. 


256 BULLETIN No. 186 [ February, 


Southern Species 


Forbesi: cherry, peach, and apple. 

Micans: persimmon and oak. 

Bipartita: willow, hickory, and oak. : 
Fraterna: oak, hickory, and persimmon. 

Profunda: oak, hickory, and persimmon. 

Crenulata: persimmon, willow, and hickory. 

Corrosa: persimmon, oak, and hickory. 

Delata: oak and hickory. 

Forsteri: oak, hickory, and persimmon. 

Praetermissa: oak, willow, and apple. 


SUMMARY 


This paper presents a survey of the species, numbers, dates of 
occurrence, food-plants, and Illinois distribution of the genus Phyl- 
lophaga (May-beetles), based on a study of nearly 119,000 specimens 
collected in forty-two counties in all but one of the nine years from 
1905 to 1913 inclusive. 

Thirty-four species of May-beetles are recognized in Illinois. 
They vary greatly in abundance, the above collection containing but 
two specimens of the rarest species and 43,349 of the commonest. 
Ninety-one percent of the specimens collected belonged to ten of the 
species, the other 9 percent being distributed among the twenty-four 
species remaining. 

A detailed discussion of the species, taken separately, shows for 
each its numbers in each year and in each of the three sections of the 
state, the dates, in each year, of its first appearance and its greatest 
abundanee, and its comparative numbers on each of its food-plants. 
By means of the data of numbers and distribution, the dominant and 
subdominant species are distinguished for each year and district, and 
the intervals between their periods of greatest abundance are con- 
sidered with reference to the length of the life cycle of the species 
concerned. 

From a comparison of the May-beetles derived from northern, 
central, and southern Illinois, respectively, it appears that three spe- 
cies are practically limited to northern Illinois, three to the northern 
and central parts of the state, two to the central and southern, and 
eleven to southern Illinois. The actual boundary lines between these 
areas of distribution are, however, irregular and meandering, espe- 
cially that between southern and central [linois, which is influenced 
by the course of the streams, the southern species following them 
northward towards their headwaters in a way to bring several such 
species far into the central division of the state. 

The seasonal succession of the species—that is the order in which 
they make their first appearance in spring—is worked out for each 
section of the state as carefully as the wide distribution and irregular 
time limits of the collections will permit. 


ERRATA 


In table on page 239, in column of remarks, against arkansana 
strike out = near bipartita; against calceata strike out = rugosa. 


Page 251, line 7, for hickory read hackberry. 








1916] MAY-BEETLES (PHYLLOPHAGA) OF ILLINOIS 257 


Generally speaking, successive periods of extraordinary abun- 
dance of a species in any locality or district show little correspondence 
to any possible life cycle, being too various and irregular for that 
interpretation. Extensive parasitism of imagos and larvae by insects, 
annelids, Protozoa, and fungi produces widespread and destructive 
epidemic diseases, a knowledge of whose prevalence and status is es- 
sential to any safe prediction of periods of destructive abundance of 
the white-grubs. 

The May-beetle species known as Phyllophaga fusca and P. futilis 
were evidently those which produced most of the white-grubs which 
were so abundant in northern []linois in 1912 as to do heavy damage 
to farm crops in several counties. Two thirds of the collections made 
in that section in 1914 were of these species, the first of. the two 
mentioned being, however, nearly four times as abundant as the 
second. 

The facts concerning the food-plants of the more abundant species 
are grouped and classified in a way to distinguish trees and shrubs 
especially attractive to them, and consequently dangerous to adjacent 
crops by reason of the abundance of white-grubs to descend from them. 


